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About Us

In the essence of spreading greenery through Riyadh, The High Commission for the Development of Arriyadh created the “Riyadh Plants” website and smart phones application, which focuses on plants suitable for agriculture through all natural conditions in the region, and an opportunity for those interested in identifying the characteristics of Afforestation in Riyadh.

Sour Seville Orange

Sour Seville Oranges grow on these medium-sized trees that may develop to a maximum height of 10 metres, achieving a round crown. Northeast India, Bangladesh and Myanmar are the presumed homelands of this species. More than 1,000 years ago it was introduced into the Mediterranean and became so popular that its vernacular name honours the Spanish town of Seville. A vigorous grower in Arriyadh, the flowers produce an unsurpassed fragrance for several weeks in spring and are a welcome feature in many gardens. Thorny twigs bear shiny, dark-green leaves that release an aromatic scent when bruised. They measure about 12 × 7 cm. The white flowers are borne in spring and may be harvested to distil perfume. Some cultivars are grown for producing essential oils that is traded as ‘neroli oil’. Pollinated blossoms are followed by yellow-orange fruits that measure up to 8 cm across. The acidic, bitter pulp contains a large number of white seeds, and is enclosed by strongly aromatic peel. In orchards, the trees are spaced some 5 metres apart. The plant is tolerant of almost any kind of soil and is therefore sometimes used to bear graftings of more delicate citrus species. Heat is tolerated with appropriate soil humidity. Brief frosts do not harm healthy plants seriously, but soft leaves and non-lignified branches may be damaged. They take severe pruning and even recover from being coppiced. Sour Seville Oranges may be propagated by seeds for ornamental purposes and by grafting if cultivars are to retain certain characteristics.

Butter fly Tree, khof al gamal

The Butterfly Tree, or khof al gamal in Arabic, is native to southeast Asia and thrives well in hot, subtropical and tropical climates. It is one of the most desirable of small trees with a fast growth, reaching a maximum height of 6 to 10 metres, and a similar width. ere are many rather isolated occurrences of the tree in Arriyadh, but it will really look its best only in a protected environ- ment with shelter, high relative humidity and frequent irrigation. Foliage remains on the tree in mild winters, to be shed when the extraordinary flowers appear. Cold winters may induce a brief period of dormancy when the twigs become bare. Inorescences resemble orchids in colours from pink to magenta. ey measure some 12 cm across, attract bees and emit a light fragrance. Its fruits are brown pods 30 cm in length, lled with spherical seeds. ese easily germinate in sandy soil. e light-green leaves are bi-lobed, like a camel’s foot. ey sprout soon after flower- ring begins. Growth habit is an open canopy with arched branches, and Butterfly Trees are often multi-stemmed or grow as a shrub. e plants should not be exposed to wind. Pruning in winter is possible to achieve the desired shape and it is recommended for young plants in particular. Flower frequent irrigation, sufficient nutrients, good drainage and full sun will ensure a good appearance. It will survive drought, but becomes stunted and will not flower if humidity is too low. Bauhinias are ideal trees in urban areas and pedestrian precincts even in containers.

Baby Sun-Rose

This succulent perennial groundcover is native to South Africa and belongs to the ice plant family (Aizoaceae, formerly Mesembryanthemaceae). It retains its fleshy leaves all year round. They are heart-shaped, about 3 cm long and their bright green contrasts well with the tiny but numerous magenta flowers that appear in summer and autumn. They consist of string-like petals that enclose a small white centre, and open only during sunshine when they attract bees and butterflies. Flowers are borne in the leaf axils and develop into capsules about 1 cm in size. Plants will not exceed 10 cm height, but stems quickly grow to 60 cm in length. It tolerates full sun when the soil is gritty and not too dry. Even though its succulent leaves store water, A. cordifolia does not revel in heat or reflected sun. The plants may even become cholorotic and can eventually expose unsightly bare twigs that will not recover properly. Light frosts, as may occur in Arriyadh, do not harm this plant. In rock gardens, it makes an excellent groundcover. It does well in containers too, where it looks best spilling over the edge. Pruning is easy and possible at any time. Propagation by cuttings is simple and seeds also germinate well. There are variegated types or cultivars with different blossom colours such as white, yellow, red and violet. A. cordifolia is best planted in small areas in Arriyadh, where it can be used as a groundcover, in a rockery, a hanging basket or cascading over the edge of a container.

Chinese Laurel Fig

This Ficus is a curiosity in that it is usually grown commercially as a bonsai tree. It was first seen in containers in Arriyadh nurseries and has been planted outside shops and restaurant windows principally because it grows compactly and can easily be pruned to shape. Often available in a spherical shape on a stem, F. panda shares all of the requirements of F. m. var. nitida, and the same applies to its ability to withstand frost and sun. It has light, almost round, thick leaves, which alternate up the stem and a brown to reddish bark dotted with small horizontal flecks. It can be propagated easily from cuttings. It suffers from several diseases, including black fly, scale, thrips and eelworm, as well as fungus and rot. Probably a variety of Ficus microcarpa, it seems to have originated in nurseries catering for indoor plants and was then exported to nurseries in the Gulf States, where it has thrived in the coastal climate and made an excellent hedge plant. In the US, two new forms of F. microcarpa entered the Florida trade in the mid 1970s (CE) under the names Ficus ‘Green Island’ and Ficus microcarpa var. crassifolia ‘Green Mound’. Both have been sold as Ficus ‘Panda’ or Ficus americana ‘Panda’ in Europe. They tend to spread out and are easy to train as a ground-hugging shrub. For best results, F. panda is best planted in a sheltered position, in the humid environment of a well-irrigated garden. F. panda is also a good screening or background shrub that needs almost no pruning to stay dense and trim.

White Karee, Willow Karee

Several species of Rhus, which are native to arid regions such as the deserts of Arizona and Mexico, and also South Africa, have potential for use in Arriyadh. Renamed Searsia pendulina in 2008, the White Karee, originating from and now widely planted in South Africa, is a small ornamental tree which can be found in Arriyadh’s nurseries. Fast-growing and somewhat short-lived, it will reach a height of about 6 metres and a spread of 4 to 5 metres. It has a willowy appearance with a rounded crown, and many drooping, weeping branches, usually on a single trunk, the bark of which is smooth and greyish, becoming rough and scaly at maturity. The dark-green leaves are trifoliate. Small, yellowish-green flowers bloom delicately on branching panicles from spring through to summer, attracting bees and butterflies. (Male and female flowers are borne on separate trees.) The edible fruits are small round berries which ripen from red to black, and are eaten by birds. The plant prefers moist soil with good drainage, and flourishes in full sun: it is wind- and drought-resistant, and relatively frost-hardy. Propagation is easy from seed and cuttings. Regular irrigation is necessary until establishment, with deep watering later during the summer months. The wood is durable and is used for fencing poles. An excellent small garden tree for shade, the roots are not aggressive, so that planting at a reasonable distance from swimming pools or patios is not a problem. Because not much pruning is needed, it makes a low-maintenance street tree.

Seacoast Mallow

The Seacoast Mallow is found growing wild in subtropical, coastal regions of southern Asia. It is an ornamental tree attaining up to 10 metres in height and width and, owing to its provenance along watercourses, it tolerates stagnant water better than other trees. High salinity and even brackish water are tolerated. It grows fast in a variety of soils and tolerates some drought, but does not appreciate low atmospheric humidity combined with prolonged dryness. Leaves are heart-shaped, evergreen and make a dense crown. Bright-yellow petals form a cup some 15 cm across with a long carpel protruding from a crimson centre. After just one or two days, they are shed, so that trees are not ideal canopies for pedestrian precincts. Often, they turn orange or red before they are dropped. Apart from this bad habit, there are no further disadvantages, so that this species is often seen as an appealing street tree. Seeds should be stratified and soaked in warm water prior to sowing, and hardwood cuttings also grow readily to imitate the traits of the parent plant. The latter will also flower sooner than plants grown from seeds. The Seacoast Mallow is a vigorous plant that does well in containers. It withstands pruning and may be kept as a small standard or used as a hedge for screening. For flowering, it requires plenty of light, and frequent irrigation with occasional fertilisation is recommended. Light frosts may damage the leaves, but plants recover quickly. There is often confusion in Arriyadh between this plant and Thespesia populnea.

Fiddlewood

Citharexylum spinosum syn. quadrangulare is an evergreen, medium-sized tree, which grows to a height of 15 metres and is beautiful because of its long tassels of richly scented, white flowers. It has, no spines, but smooth, quadrangular twigs. The bark is light brown, and becomes fissured with maturity. Its common name is Fiddlewood and it is a native of the West Indies, where it generally grows in wet habitats below 500 metres elevation in agricultural, coastland and urban areas. Leaves are ovate and have orange petioles. They turn an orange-brown colour during the dry season, and without regular irrigation the tree can be deciduous. Flowers borne in racemes cover the tree from spring to autumn. The fruits are red to black drupes. Hardy to –6°C, C. spinosum requires full sun to partial shade and grows in most soils, preferring neutral to mildly alkaline, well-drained soils. Fiddlewood trees should not be overwatered. Propagation is best from woody stem cuttings or seeds. Easy to grow, and with its dark-green, shiny and ornamental foliage, it makes a good tree for landscape use. It does, however, have major disadvantages in that all parts of the plant are poisonous and it may become an invasive, noxious weed. C. spinosum is a tree that is now being planted in Arriyadh for its aesthetic appeal. Its roots are very aggressive. Regular pruning is necessary to shape trees. If removal of the tree is desired, it is necessary that the whole root mass also be removed, since C. spinosum will grow back quickly from a cut down trunk.

Elephant Vine, Woolly Morning Glory

Benjamina, Weeping Fig

The Weeping Fig, native to southeast Asia, is a lushly tropical and elegant tree, more likely to be found as an indoor plant in Arriyadh than growing outdoors. Popular throughout the world in homes, offices and shopping malls, F. benjamina will withstand Arriyadh’s climate, but only when fully protected in a garden. In the past, it was occasionally found outdoors, but heavy frosts and scorching sun in recent years have caused its disappearance. With its dense foliage and gracefully weeping branches, it will grow relatively quickly in a favourable location to a height of 15 metres with equal spread. Glossy, dark-green, ovate leaves with pointed tips grow up to 10 cm long. The fruit is very small and red when ripe. In Arriyadh it is best in a warm-winter patio or garden in semi-shade. F. benjamina prefers deep, moist soils with good drainage and requires regular irrigation, more during the first years, and after establishment it will withstand short periods of drought. It needs wind protection when young. Propagation is by cuttings or air-layering. Occasionally cholorotic in Arriyadh’s soils, trees are prone to attacks by mealybugs. Expanding roots can be invasive and cause damage to underground pipes and paving; they also make it difficult for other plants to grow close by. As accent or focal point trees, they are also very attractive in containers. Trees can be clipped to shape and regular pruning will improve appearance, but pruning must be drastic if the branches are caught by a hard frost.

Ziziphus, Crown of thorns, sidr

Ziziphus spina-christi has the common names Ziziphus and Crown-of-Thorns. This tree is indigenous to the east Mediterranean basin and southwest Asia. The Ziziphus has a normal growth rate and develops a dense, often multi-stemmed crown. The semi-evergreen foliage is green; the leaves are alternately arranged, entire and ovate in shape. The branches are armed with small thorns. Z. spina-christi reaches a height up to 14 metres, with a width of up to 9 metres. The root system is deep and extensive. The flowers are inconspicuous and umbel-like, with a light yellow-green colour. After flowering, the tree develops apple-like fruits with a size of about 1 cm. These are initially yellow, and later brown-red in colour. The tree is propagated by sowing and pricking, or by cuttings. Z. spina-christi is one of the best and most reliable trees used in Arriyadh landscape design. It can be found growing well everywhere in the city, e.g. in King Fahd Road, as a street tree in Murrabba and in Addiriyyah. It is completely adapted to harsh desert and urban conditions, needs almost no maintenance, low irrigation, little pruning and no added nutrients. It can withstand medium salinity, but does not appreciate stagnant water. The tree is very valuable for urban areas as a shelter plant, for public open spaces, street planting, parks and private gardens, and also for roof gardens and courtyards. The only thing that needs to be considered is the fruit drop. Ziziphus is good as a specimen tree and for afforestation and roadside planting.

Moses-in-the-cradle, Boat Lily

Boat Lilies are stout perennials with upright shoots up to about 40 cm in height. They grow in clumps with lush-green leaves some 30 cm long. From beneath, the lance-shaped foliage is burgundy-purple, creating an interesting contrast. Their origin is southern Mexico, Belize, Guatemala and the West Indies, where they flower all year round. In Arriyadh, small flowers appear whenever conditions are favourable, from boat-like cradles to eventually develop to round seeds. These easily germinate to form plenty of seedlings, ultimately creating dense mats. It is possible to prick these offspring or take cuttings from stems or leaves to propagate Boat Lilies. They grow readily in a wide range of soils, as long as these are well-drained, and they tolerate diverse light conditions ranging from full sun to partial shade. Although these perennials re-grow after nipped back by frost, exposed sites should be avoided. In time, the plants become dense clumps which can be used as border plants, areal cover, mass planting or group planting with a spacing of between 30 cm and 60 cm. They do well in containers and are popular house plants, but they are susceptible to the effects of stagnant water and prolonged drought. A cultivar named ‘Variegata’ has cream-coloured stripes and less vigour than the species. It must not be exposed to full sun, because the variegation will soon be sunburnt. Plants should be handled with care, especially if cut or bruised, since the sap may cause skin problems.

Guava, Guave

From tropical America, this tender shrub has spread to all warm climates in the world. In favourable conditions, it may grow to a specimen tree of 7 metres in height. Veined, evergreen leaves are arranged oppositely on four-angled twigs. The emerging foliage is reddish to protect it from intense sun. When the reddish elderly bark peels off, it exposes light-grey bark beneath. A common tropical feature is flowers and fruit found on the tree at the same time. In Arriyadh, where the tree is often found in cultivation on farms, the white flowers appear mainly in spring, measuring about 2 to 3 cm across. Guaves are self-fertile, so that one plant does not need a neighbour for fertilisation. The fruits vary considerably in size, shape, colour and taste: they are between 5 and 10 cm in diameter, round or elongated, grey, white or pink, with more or less taste, either sweet or insipid. They turn ripe in autumn or early winter, emitting an intense pleasant scent. Guave fruits can be eaten fresh or processed to make juice and jam. Cultivars usually contain plenty of seeds within the pulp, but a few varieties are almost seedless. They germinate readily so that plants sometimes naturalise where conditions are met. In humid, warm regions, they may become weedy. Guave trees do well in full sun, but resent strong winds and reflected heat. Young plants are tender to cold, but mature trees tolerate brief, light frosts. Any well-drained soil is welcomed, either acidic or alkaline, but a high level of humus is appreciated.

Garden Geranium, Zonal Geranium

Garden Geraniums are hybrids of various South African species. They are small, erect shrubs with herbaceous branches on a woody base reaching a maximum of about 90 cm in height and some 70 cm in width, depending on the cultivars. Evergreen, fleshy foliage covers the plant densely. The leaf edges are lobed, and the dull green upper side often shows a ring of purple or brown. Terminal clusters of striking flowers are available in a wide range of colours such as red, pink, lilac, violet, orange and white. A single inflorescence usually consists of five petals, but double flowers have many more. Although the flowering climax is in spring, flowers may be seen all year round, if spent clusters are cut off frequently both for a neat appearance and to induce the development of new buds. Garden Geraniums enjoy sunny locations, but will also do well in partial sun. The soil should drain well and offer enough nutrients for the plant’s vigorous growth. The plant takes some drought, but looks best if watered frequently. Light frosts are tolerated, but severe cold kills the entire plant. Pruning can be done at any time to replace the brittle stems by young shoots. Cuttings can be taken both in spring and in autumn. Sowing is a year-round alternative. These Geraniums are the ideal plants for pots, containers and beddings. They enhance mixed borders with splendid colours and suit both public and private sites. Regularly seen throughout the year in Arriyadh, they are most prominent when they are planted for a winter colour display.

Cairo Morning Glory, Mile-a-Minute Vine

Chinese Hibiscus

Since it is no longer found in the wild, the origin of this plant is uncertain, although sinensis indicates a Chinese background. This was once a very common shrub in Arriyadh, but its susceptibility to frost, disease and insects seems to have made it rare. Various cultivars exist, with single or double flowers in shades of white, yellow, pink, orange and red. It is very easy to multiply Chinese Hibiscus by hardwood cuttings of 20 cm in length when the leaves are reduced to a third and the sticks are covered to retain humidity. Brief periods of frost may damage the twigs, but the bushes quickly recover and also flower within the same year. Annual cutting back, exhaust fumes and considerable dryness are tolerated, but they may result in slow growth and a reduction of flowering. Even some salinity is tolerated, but the leaves show chlorosis and may even be dropped. This species is usually evergreen and produces dark-green, shiny foliage. In its native habitat, Chinese Hibiscus flowers all year round. Elsewhere, flowers are produced when temperatures exceed 18°C. Above 25°C, the flowering is reduced, so that Chinese Hibiscus in Arriyadh flowers in spring and in autumn, but rarely in summer. In dry areas, the plants appreciate an occasional spray with the garden hose. Fertiliser should be applied frequently to encourage a prolonged period of blossom. When the leaves turn yellow between the veins, iron chelate is the appropriate remedy. Usually this chlorosis appears where the ground is alkaline and lacks humus.

Trailing Gazania

The Trailing Gazania does not present as spectacular flowers as its relatives, but still makes one of the most useful perennials to have. It grows wild in South Africa and Mozambique; in Arriyadh, it is a very dependable groundcover. In parks and large gardens with adverse growing conditions such as dry, exposed sites, it performs better than other groundcovers. It grows prostrate and blankets the bare ground fairly quickly. The glabrous leaves are long and slender, appearing green in light shade, but somewhat silvery if fully exposed to sunlight. They persist in winter and withstand low temperatures and even light frosts, but they sometimes look poor in scorching heat. Drought is tolerated, but the plants appreciate occasional watering. In spring and summer, bright yellow flowers with centres in the same colour appear, measuring about 3 to 4 cm across. Removing spent flowers results in extra inflorescences. They close during the night and do not open on overcast days. After pollination, they develop fuzzy, white seeds. These readily germinate, but offspring may also be achieved by cuttings or division, when the stems root where they touch the soil. This Gazania is the ideal plant to grow over dry banks or to cascade over walls or edges of tubs. It may be clipped to shape, creating cutwork parterres. It is generally pest-free and resists diseases if good air circulation is possible. Flowers close if water is applied by sprinklers. On appropriate sites, the Trailing Gazania is almost maintenance-free.

Indian Laurel

The Indian Laurel is another species of Ficus, which has largely disappeared from Arriyadh, owing to its lack of frost tolerance. Native to India, it is often found in North Africa and the Middle East growing as a majestic shade tree. In Arriyadh, however, the species was formerly used to line many streets, and was often seen in clipped shapes on the lawns of parks during the 1970s (CE). Since then, the trees have slowly become less prominent in the city, as heavy frosts took their toll. It grows at a moderate rate to a height of 8 metres, and equal spread with strongly ascending, erect branches and smooth, glossy bright green leaves. Tolerant of many soils, it grows well in sand and does best in a fertile, moist soil. Tolerance to salinity is only medium. F. microcarpa var. nitida requires full sun and is tolerant of high temperatures and low humidity, although it thrives better with high humidity, as in Jeddah. It should be irrigated regularly in summer and will require deep watering only occasionally in the winter. Propagation is by cuttings and air-layering. F. microcarpa var. nitida is a variety of F. microcarpa (also known as F. retusa), which has larger leaves and longer, pendulous branches. Like many other Ficus species, its roots can be aggressive and buckle hard paving. Indian Laurel is prone to attacks by mites, mealybugs, thrips and scale. Suitable for gardens and containers, it is an excellent tree for public open spaces, and pathway shade, where the winters are warm and frost-free.

Crown of Thorns

This succulent is native to Madagascar: it is often seen in Arriyadh in planters, usually with the intention of forming a barrier. Its edged stems are fleshy and able to store water while the foliage is not thickened. The obovate, dark-green leaves are found on new growth only. Male and female flowers are borne on the same plant, but both are inconspicuous. Nevertheless, a burst of colour is shown in spring by bright-red bracts. Sparse flowering appears during the other seasons too. It is attractive all year round for its strange appearance of thorny shoots that made it deserve the common name Crown of Thorns. Injured plants exude a milky, poisonous sap that can irritate skin. Pruning is not necessary, but is carried out to multiply the plant by cuttings. For this purpose, tips of 10 cm length are cut and placed in water until the sap stops flowing. Afterwards, they should be allowed to dry before being dipped in rooting hormone and placed in a mix of sand, perlite and humus. Excellent drainage is essential for mature plants too, since both waterlogging and overwatering by sprinklers kill the plant, especially in winter. Partial sun suits it best and extends the lifespan of the foliage. Drought is tolerated when the plants are established, but it also limits the endurance of the leaves. Slow-releasing fertilisers can be applied in spring to ensure a healthy appearance and an impressive floral display. Scale insects may infest plants on inappropriate sites. Frosts are not tolerated and immediately damage the foliage.

Umbrella Plant

The Umbrella Plant is a grass-like, subtropical perennial native to southern Africa and Madagascar. Now regularly seen in Arriyadh, it was previously observed or was planted close to water, but now seems to have ‘escaped’ and has seeded itself successfully in drier soils. It grows upright culms with flat, linear leaves radiated on top. The plants are evergreen and grow to 1 metre in height. Ideal habitats are moist with a high nutrient content. Spreading rhizomes form huge clumps that may capture riverbanks and pond-sides. In summer, plain, brown flowers occur on top of the whorls. Umbrella Plants are grown for their picturesque appearance. They give a lush, exotic impact next to any kind of water feature. They are one of the few plants adapted to waterlogged sites, but also tolerate locations with average moisture, where they are less invasive. Partial sun suits them best. Frost kills the plant’s foliage but it revives as soon as temperatures rise again in spring. They are readily propagated by seeds or may be divided at any time of the year. Maintenance is limited to the occasional removal of dead or unsightly leaves. If neglected in suitable environments, small, shallow ponds and swamps may be overgrown. Umbrella Plants are generally traded as Cyperus alternifolius or mistaken for their larger relatives, Papyrus. A dwarf type is Cyperus involucratus f. gracilis, with a height of some 30 cm suitable for containers and even pots to grow indoors. A cultivar called ‘Variegatus’ reaches about 1.2 metres and has white leaf margins.

Painted Nettle

The Painted Nettle is one of the most popular plants for interior greening, and is widely used outdoors where its conditions are met. They are tender perennials from southeast Asia found in shady, humid environments. If grown as bedding plants, they create masses of multi-coloured foliage to a height of about 30 cm. They are more valued when planted in mixed borders, where they grow twice as high to form a round, bushy eye-catcher. The variegation is outstanding, in shades of green, yellow, scarlet, red, pink and ivory. Terminal flower spikes feature azure florets that are usually pinched out, since the foliage is this plant’s main, spectacular attraction. In Arriyadh’s winters, Painted Nettles take full sun, but during the summer they are best sheltered, especially during the afternoons. Frost instantly kills this plant, and strong winds twist the leaves or entire branches. It appreciates fertile soil with ample water, but without waterlogging. It is very easy to grow in pots and containers. The easiest method of propagation is by placing cuttings in water or planting them in a mixture of peat, compost and sand with some cover to reduce transpiration. Sowing is an alternative in order to pick one of many colourful varieties, or to achieve random forms. They respond well to fertilising and do best with occasional pruning to rejuvenate the stems. Frequent pinching is recommended to form a denser habit. Their moderate to high maintenance requirements limit the use of Painted Nettles to well-kept gardens and pedestrian precincts.

Croton

Better known as Croton, this evergreen shrub is widespread as a highly ornamental bush for the garden or as a popular indoor plant. It originates from India, Sri Lanka, Malaysia and Indonesia, where heat is accompanied by high atmospheric humidity and rainfall; hence, it demands abundant water. In Arriyadh, it withstands the sun and dry air relatively well, but requires a position sheltered from desiccating winds. The soil must be rich in humus and well drained. Crotons grow their colourful foliage in partial sun. High contents of nutrients and high temperatures may reduce the number of bright spots. Full sun bleaches the colours, while a lack of light results in greener leaves with less yellow or red spots. The intensely mottled foliage is shiny and attracts the eye from far, the major asset of Crotons. Plenty of varieties are bred such as ‘Petra’, with yellow veins and red shades alternating with green. Its white flowers are insignificant. Favourable conditions let it grow into a V-shaped bush of about 2.5 metres high and up to 2 metres wide. High levels of humus are important, and it should not be exposed to drying winds. Severe cutting back is possible in early spring, if frost has damaged the leaves. It does well in containers, is an ideal indoor plant and makes excellent focal points or colourful hedges. Stressed plants may occasionally be infected by mealybugs or scale. Both cuttings and layering make for strong offspring easily. In public gardens, it may as well be too exotic, but should be restricted to special sites.

Canna, Indian Shot

Cannas are beautiful, herbaceous perennials, which provide a colourful display from red to orange and yellow, when their basic needs are met: rich soil with lots of humus and plenty of water. They originate in the humid tropics, where the more than 30 different types of Canna are native to Central and South America. New cultivars have been created, particularly those with almost black foliage, or very deep-coloured red flowers and variegated leaves. An outstanding feature is that they bloom almost non-stop throughout the year. The attractive leaves are large, broad, oval, veined and rubbery-textured on glabrous stems; the roots are tuberous rhizomes. Exposure to the sun is essential, although partial shade encourages stronger growth, and a lack of light may reduce flowering. Cannas may be propagated by seed, and the fleshy rhizomes of cultivars with their bright colours require division. All parts of the plant are frost-tender. Alkaline soils with a high pH may cause chlorisis. C. indica can be used as a potted plant, or planted in herbaceous borders, on the edge of ponds, and as a patio plant. They should be set about 50 cm apart and mulching the soil helps to keep in moisture. Clumps of Cannas look more natural than massed planting. High winds tear the leaves, and so a protected location is recommended, especially in Arriyadh, where leaf scorch could potentially be a problem. Dead flowers should be cut off to stimulate new flowers. Any ungainly leaves should be removed to the ground to encourage new shoots with lush foliage.

Burning Bush, Summer Cypress

The Summer Cypress is a fast-growing annual with soft foliage that resembles a Cypress tree. During summer, it has a lush impact with its fresh, bright-green leaves, while in autumn the colour becomes a showy reddish-purple. In Arriyadh, both colours are an attractive, seasonal addition to the garden and have some use in public green areas. The leaves, are arranged alternately and are linear in shape. It is more likely that it will establish itself on disturbed sites such as roadsides and ditch banks. The thin but dense foliage, on fleshy twigs, makes the plant vulnerable to heavy rain and wind. Inconspicuous flowers with green, leaf-like bracts occur in spikes during summer. Small, oval fruits contain tiny dark-brown or black seeds. Its attraction is its lush, egg-shaped appearance and the bright colour. The plant may reach a height of 1.3 metres if conditions are favourable. It may be grown as an annual hedge for low screening, or it can even be clipped to any topiary shape. On slopes, it may be planted to control erosion. Any soil is tolerated, but stagnant water kills the plant just as a single, frosty night might also do. Alkaline soils and high salinity are not a problem, but plants look poor in periods of prolonged drought. Seeds germinate within two to three weeks. Seedlings can be grown in pots first, or the seeds may be sown directly on site. Water frequently until established. Maintenance is minimal during growth, but after a short time the plants have to be removed. Summer Cypresses are not poisonous.

Lemon-Scented Geranium

In South Africa’s Cape Province, it is possible to find Lemon Geraniums growing wild in scrub vegetation or light woodland. It is considered a sub-shrub for its herbaceous branches sprouting from a woody base to some 90 cm in height. Nevertheless, these upright bushes are also grown as annual plants in pots or beddings for combining attractive pink flowers with a pleasant fragrance. The crinkled foliage grows very dense so that plants are easily formed in any shape desired. The specific name refers to the texture of its foliage, since crispum means curly. When touched, the glandular, evergreen leaves release a strong lemon scent. They are cordate in shape and fresh green. In Arriyadh’s climate, where it makes a good garden plant, it should be protected from full sun and drying winds. Short dry periods are tolerated, but this species does better with frequent watering in well-drained soil. To guarantee appropriate moisture and allow aeration at the same time, the ground is best improved by adding compost and perlite. All-purpose fertiliser can be applied frequently. Lemon Geraniums do not take frost, extreme heat is best endured in semi-shade locations. Plants stressed by adverse growing conditions are sometimes infested by spider mites or mildew. Propagation by seed is started in late winter, while softwood cuttings may be planted in late summer. The main flowering period is spring to early summer. Some varieties have been selected with more showy flowers and another cultivar, ‘Variegatum’, features leaves with ivory margins.

Milo, Portia Tree, Seaside Mahoe

Pink Trumpet Tree

The Pink Trumpet Tree is a very beautiful, flowering tree in its native habitats of South America; in certain situations in Arriyadh, such as the King Abdulaziz Historical Centre, where the microclimate is suitable, it has become an attractive addition to the planting palette. Fast growing and deciduous, it will reach a height of up to 25 metres, in Arriyadh much less; it has a wide crown with thick, layered branches. The bark can be grey to brown and vertically fissured. Dark-green leaves are compound and finger-like: each leaf has five leaflets, the middle one being the largest. The tree begins to drop its leaves at the end of a hot, dry summer; large, purplish-pink to nearly white flowers, measuring almost 7 cm across, open in early spring. Long and slender seedpods contain many winged seeds. Fallen flowers retain the pink colour, forming a colourful carpet beneath the tree. In an arid location, the tree flowers very profusely. A moderately drought-resistant tree, T. rosea grows well in deep rich, well-drained sandy soil with variable pH values, but requires regular, abundant irrigation. It can be damaged by frost. Pests and diseases have not been observed. Propagation is by branch cuttings and seed. The Pink Trumpet Tree is a common and showy flowering tree in the tropics, and is often planted along roads, and in parks and gardens. It is an excellent shade and specimen tree for pathways. Maintenance is low: trees withstand a limited amount of pruning, but cannot be cut back hard.

Castor oil plant, kharwah

Ricinus communis has the common name of Castor Oil Plant: in Arabic, it is known as al kharwah. The area of distribution extends across Burma, northern Asia and northwest China. This annual shrub-like plant prefers tropical to sub-tropical climates, and is not frost-tolerant. Ricinus communis grows fast, and reaches a height of between 2 and 3 metres. It is often multi-stemmed. The leaves are mainly green and sometimes appear as dark red; they are whorled, entire and palmate. The flowers appear in summer in panicles with red-brown, hirsute globes. The plant is very impressive in its appearance. The fruits are capsules that contain seeds which look like ticks. The plant is named after its seeds. All parts of the plant are highly poisonous, especially the seeds. The oil from the seeds is not poisonous, and was used as a remedy. The irrigation and nutrient requirements are high. In Arriyadh, the plant can be found growing wild in the Wadi Hanifah close to the water course. Because of its poison, it is often removed, although for some this is an attractive ornamental plant; in Europe, it is used as a summer bedding plant. However, it must doubtless be controlled because of its invasive character. Susceptible to insect attack, propagation methods are direct seeding or sowing and pricking out. In landscape design, it can be recommended as a background plant. This bee-attracting plant can be planted for foliage effects in public open spaces and parks, bearing in mind that its seeds are poisonous. It also looks well in containers.

Argentine Mesquite

The Argentine Mesquite is a semi-evergreen, upright, vase-shaped tree with a broad canopy, which grows to 10 m in height and spread. P. alba together with P. chilensis and P. juliflora were introduced into the Kingdom and Gulf States as roadside trees, and for other ornamental purposes. This handsome tree is well adapted to arid habitats, and has been seen to grow well in Arriyadh. Its short trunk has a thin, greyish-brown bark. Delicate, bluish-green, bipinnate leaves with paired leaflets are more closely spaced than those of other Prosopis species. The tiny flowers, which attract bees, are yellowish catkins which bloom in spring; fruit pods are up to 20 cm long and generally highly curved. Stems and trunks sometimes bear large thorns in a zigzag fashion; the bark is dark and rough. Trees require full sun and reflected heat, and will grow in poor, alkaline, saline soils and have deep roots reaching the water table. Requiring no irrigation after establishment, periodic deep watering improves appearance. They cannot withstand a series of heavy frosts. Propagation is by seed and cuttings. Maintenance requirements are high, owing to pod, flower and leaf litter, and the plants need training, secure staking and pruning in late summer for a strong structure. P. alba has landscape value as a small shade tree, in street medians, buffer zones, screens and windbreaks, and is effective in parks, but is not suitable for lawns. Possible problems and other cultural requirements are the same as for P. juliflora.

Glow Vine

The Glow Vine is a spectacularly flowering, wide-spreading, climbing plant in the trumpet vine family, native to Colombia and Ecuador; it can also be shaped into a large shrub, with a bare stem and thick crown. A free-growing vine up to 6 metres long, it has dark-green, dense foliage. S. magnifica will grow in the protected environment of a garden in Arriyadh. The stems are almost round in cross-section, and marked with longitudinal stripes. The elliptical, smooth, leathery leaves have two unequal leaflets with rounded ends, and another two leaflets at the base of the stalk. They have an orange-red colouring during the winter. The magenta, scented panicles of large, bell-shaped flowers, have hairy, yellow throats and magenta nectar lines. These bright flowers appear from spring to autumn. The fruit is a long, flattened capsule. Glow Vine prefers cultivated, deep, but well-drained, moist soil with plenty of humus. Propagation is from seed and cuttings. It requires a hot, sunny position with some light shade, especially in Arriyadh; it is also frost-tender and needs protection from the wind. Regular watering is necessary, and deep watering every four weeks in summer is vital. Mature organic fertiliser added to the soil every year in spring is recommended. S. magnifica is prone to fungal diseases, which should be treated pre-emptively with a systemic fungicide; an insecticide should be applied to prevent the attack of aphids and cochineals before the hot weather begins. Otherwise, the Glow Vine needs little maintenance.
  • Trees
  • Shrubs (Sub-shrubs)
  • Climbers
  • Herbsaceous Plants
  • Palms, Cycads
  • Cacti, Succulents
  • Aquatic Plants

Sour Seville Orange

Sour Seville Oranges grow on these medium-sized trees that may develop to a maximum height of 10 metres, achieving a round crown. Northeast India, Bangladesh and Myanmar are the presumed homelands of this species. More than 1,000 years ago it was introduced into the Mediterranean and became so popular that its vernacular name honours the Spanish town of Seville. A vigorous grower in Arriyadh, the flowers produce an unsurpassed fragrance for several weeks in spring and are a welcome feature in many gardens. Thorny twigs bear shiny, dark-green leaves that release an aromatic scent when bruised. They measure about 12 × 7 cm. The white flowers are borne in spring and may be harvested to distil perfume. Some cultivars are grown for producing essential oils that is traded as ‘neroli oil’. Pollinated blossoms are followed by yellow-orange fruits that measure up to 8 cm across. The acidic, bitter pulp contains a large number of white seeds, and is enclosed by strongly aromatic peel. In orchards, the trees are spaced some 5 metres apart. The plant is tolerant of almost any kind of soil and is therefore sometimes used to bear graftings of more delicate citrus species. Heat is tolerated with appropriate soil humidity. Brief frosts do not harm healthy plants seriously, but soft leaves and non-lignified branches may be damaged. They take severe pruning and even recover from being coppiced. Sour Seville Oranges may be propagated by seeds for ornamental purposes and by grafting if cultivars are to retain certain characteristics.

Butter fly Tree, khof al gamal

The Butterfly Tree, or khof al gamal in Arabic, is native to southeast Asia and thrives well in hot, subtropical and tropical climates. It is one of the most desirable of small trees with a fast growth, reaching a maximum height of 6 to 10 metres, and a similar width. ere are many rather isolated occurrences of the tree in Arriyadh, but it will really look its best only in a protected environ- ment with shelter, high relative humidity and frequent irrigation. Foliage remains on the tree in mild winters, to be shed when the extraordinary flowers appear. Cold winters may induce a brief period of dormancy when the twigs become bare. Inorescences resemble orchids in colours from pink to magenta. ey measure some 12 cm across, attract bees and emit a light fragrance. Its fruits are brown pods 30 cm in length, lled with spherical seeds. ese easily germinate in sandy soil. e light-green leaves are bi-lobed, like a camel’s foot. ey sprout soon after flower- ring begins. Growth habit is an open canopy with arched branches, and Butterfly Trees are often multi-stemmed or grow as a shrub. e plants should not be exposed to wind. Pruning in winter is possible to achieve the desired shape and it is recommended for young plants in particular. Flower frequent irrigation, sufficient nutrients, good drainage and full sun will ensure a good appearance. It will survive drought, but becomes stunted and will not flower if humidity is too low. Bauhinias are ideal trees in urban areas and pedestrian precincts even in containers.

Indian Laurel

The Indian Laurel is another species of Ficus, which has largely disappeared from Arriyadh, owing to its lack of frost tolerance. Native to India, it is often found in North Africa and the Middle East growing as a majestic shade tree. In Arriyadh, however, the species was formerly used to line many streets, and was often seen in clipped shapes on the lawns of parks during the 1970s (CE). Since then, the trees have slowly become less prominent in the city, as heavy frosts took their toll. It grows at a moderate rate to a height of 8 metres, and equal spread with strongly ascending, erect branches and smooth, glossy bright green leaves. Tolerant of many soils, it grows well in sand and does best in a fertile, moist soil. Tolerance to salinity is only medium. F. microcarpa var. nitida requires full sun and is tolerant of high temperatures and low humidity, although it thrives better with high humidity, as in Jeddah. It should be irrigated regularly in summer and will require deep watering only occasionally in the winter. Propagation is by cuttings and air-layering. F. microcarpa var. nitida is a variety of F. microcarpa (also known as F. retusa), which has larger leaves and longer, pendulous branches. Like many other Ficus species, its roots can be aggressive and buckle hard paving. Indian Laurel is prone to attacks by mites, mealybugs, thrips and scale. Suitable for gardens and containers, it is an excellent tree for public open spaces, and pathway shade, where the winters are warm and frost-free.

Ziziphus, Crown of thorns, sidr

Ziziphus spina-christi has the common names Ziziphus and Crown-of-Thorns. This tree is indigenous to the east Mediterranean basin and southwest Asia. The Ziziphus has a normal growth rate and develops a dense, often multi-stemmed crown. The semi-evergreen foliage is green; the leaves are alternately arranged, entire and ovate in shape. The branches are armed with small thorns. Z. spina-christi reaches a height up to 14 metres, with a width of up to 9 metres. The root system is deep and extensive. The flowers are inconspicuous and umbel-like, with a light yellow-green colour. After flowering, the tree develops apple-like fruits with a size of about 1 cm. These are initially yellow, and later brown-red in colour. The tree is propagated by sowing and pricking, or by cuttings. Z. spina-christi is one of the best and most reliable trees used in Arriyadh landscape design. It can be found growing well everywhere in the city, e.g. in King Fahd Road, as a street tree in Murrabba and in Addiriyyah. It is completely adapted to harsh desert and urban conditions, needs almost no maintenance, low irrigation, little pruning and no added nutrients. It can withstand medium salinity, but does not appreciate stagnant water. The tree is very valuable for urban areas as a shelter plant, for public open spaces, street planting, parks and private gardens, and also for roof gardens and courtyards. The only thing that needs to be considered is the fruit drop. Ziziphus is good as a specimen tree and for afforestation and roadside planting.

Benjamina, Weeping Fig

The Weeping Fig, native to southeast Asia, is a lushly tropical and elegant tree, more likely to be found as an indoor plant in Arriyadh than growing outdoors. Popular throughout the world in homes, offices and shopping malls, F. benjamina will withstand Arriyadh’s climate, but only when fully protected in a garden. In the past, it was occasionally found outdoors, but heavy frosts and scorching sun in recent years have caused its disappearance. With its dense foliage and gracefully weeping branches, it will grow relatively quickly in a favourable location to a height of 15 metres with equal spread. Glossy, dark-green, ovate leaves with pointed tips grow up to 10 cm long. The fruit is very small and red when ripe. In Arriyadh it is best in a warm-winter patio or garden in semi-shade. F. benjamina prefers deep, moist soils with good drainage and requires regular irrigation, more during the first years, and after establishment it will withstand short periods of drought. It needs wind protection when young. Propagation is by cuttings or air-layering. Occasionally cholorotic in Arriyadh’s soils, trees are prone to attacks by mealybugs. Expanding roots can be invasive and cause damage to underground pipes and paving; they also make it difficult for other plants to grow close by. As accent or focal point trees, they are also very attractive in containers. Trees can be clipped to shape and regular pruning will improve appearance, but pruning must be drastic if the branches are caught by a hard frost.

Fiddlewood

Citharexylum spinosum syn. quadrangulare is an evergreen, medium-sized tree, which grows to a height of 15 metres and is beautiful because of its long tassels of richly scented, white flowers. It has, no spines, but smooth, quadrangular twigs. The bark is light brown, and becomes fissured with maturity. Its common name is Fiddlewood and it is a native of the West Indies, where it generally grows in wet habitats below 500 metres elevation in agricultural, coastland and urban areas. Leaves are ovate and have orange petioles. They turn an orange-brown colour during the dry season, and without regular irrigation the tree can be deciduous. Flowers borne in racemes cover the tree from spring to autumn. The fruits are red to black drupes. Hardy to –6°C, C. spinosum requires full sun to partial shade and grows in most soils, preferring neutral to mildly alkaline, well-drained soils. Fiddlewood trees should not be overwatered. Propagation is best from woody stem cuttings or seeds. Easy to grow, and with its dark-green, shiny and ornamental foliage, it makes a good tree for landscape use. It does, however, have major disadvantages in that all parts of the plant are poisonous and it may become an invasive, noxious weed. C. spinosum is a tree that is now being planted in Arriyadh for its aesthetic appeal. Its roots are very aggressive. Regular pruning is necessary to shape trees. If removal of the tree is desired, it is necessary that the whole root mass also be removed, since C. spinosum will grow back quickly from a cut down trunk.

Seacoast Mallow

The Seacoast Mallow is found growing wild in subtropical, coastal regions of southern Asia. It is an ornamental tree attaining up to 10 metres in height and width and, owing to its provenance along watercourses, it tolerates stagnant water better than other trees. High salinity and even brackish water are tolerated. It grows fast in a variety of soils and tolerates some drought, but does not appreciate low atmospheric humidity combined with prolonged dryness. Leaves are heart-shaped, evergreen and make a dense crown. Bright-yellow petals form a cup some 15 cm across with a long carpel protruding from a crimson centre. After just one or two days, they are shed, so that trees are not ideal canopies for pedestrian precincts. Often, they turn orange or red before they are dropped. Apart from this bad habit, there are no further disadvantages, so that this species is often seen as an appealing street tree. Seeds should be stratified and soaked in warm water prior to sowing, and hardwood cuttings also grow readily to imitate the traits of the parent plant. The latter will also flower sooner than plants grown from seeds. The Seacoast Mallow is a vigorous plant that does well in containers. It withstands pruning and may be kept as a small standard or used as a hedge for screening. For flowering, it requires plenty of light, and frequent irrigation with occasional fertilisation is recommended. Light frosts may damage the leaves, but plants recover quickly. There is often confusion in Arriyadh between this plant and Thespesia populnea.

White Karee, Willow Karee

Several species of Rhus, which are native to arid regions such as the deserts of Arizona and Mexico, and also South Africa, have potential for use in Arriyadh. Renamed Searsia pendulina in 2008, the White Karee, originating from and now widely planted in South Africa, is a small ornamental tree which can be found in Arriyadh’s nurseries. Fast-growing and somewhat short-lived, it will reach a height of about 6 metres and a spread of 4 to 5 metres. It has a willowy appearance with a rounded crown, and many drooping, weeping branches, usually on a single trunk, the bark of which is smooth and greyish, becoming rough and scaly at maturity. The dark-green leaves are trifoliate. Small, yellowish-green flowers bloom delicately on branching panicles from spring through to summer, attracting bees and butterflies. (Male and female flowers are borne on separate trees.) The edible fruits are small round berries which ripen from red to black, and are eaten by birds. The plant prefers moist soil with good drainage, and flourishes in full sun: it is wind- and drought-resistant, and relatively frost-hardy. Propagation is easy from seed and cuttings. Regular irrigation is necessary until establishment, with deep watering later during the summer months. The wood is durable and is used for fencing poles. An excellent small garden tree for shade, the roots are not aggressive, so that planting at a reasonable distance from swimming pools or patios is not a problem. Because not much pruning is needed, it makes a low-maintenance street tree.

Pink Trumpet Tree

The Pink Trumpet Tree is a very beautiful, flowering tree in its native habitats of South America; in certain situations in Arriyadh, such as the King Abdulaziz Historical Centre, where the microclimate is suitable, it has become an attractive addition to the planting palette. Fast growing and deciduous, it will reach a height of up to 25 metres, in Arriyadh much less; it has a wide crown with thick, layered branches. The bark can be grey to brown and vertically fissured. Dark-green leaves are compound and finger-like: each leaf has five leaflets, the middle one being the largest. The tree begins to drop its leaves at the end of a hot, dry summer; large, purplish-pink to nearly white flowers, measuring almost 7 cm across, open in early spring. Long and slender seedpods contain many winged seeds. Fallen flowers retain the pink colour, forming a colourful carpet beneath the tree. In an arid location, the tree flowers very profusely. A moderately drought-resistant tree, T. rosea grows well in deep rich, well-drained sandy soil with variable pH values, but requires regular, abundant irrigation. It can be damaged by frost. Pests and diseases have not been observed. Propagation is by branch cuttings and seed. The Pink Trumpet Tree is a common and showy flowering tree in the tropics, and is often planted along roads, and in parks and gardens. It is an excellent shade and specimen tree for pathways. Maintenance is low: trees withstand a limited amount of pruning, but cannot be cut back hard.

Milo, Portia Tree, Seaside Mahoe

Sweet Thorn

Endemic to southern Africa, A. karroo has been selected from the exotic acacias as having potential for planting in Arriyadh. Typically a shrub, it will grow into a medium-sized tree under good conditions and grows rapidly with regular water. Variable in shape and size, it has a rounded crown, branching from the lower part of the trunk. The bark has deep fissures and is red on young branches. Fragrant, yellow flowers, opening in clustered heads in late spring. Narrow seed pods are flat, straight or curved. A. karroo is a pioneer tree with an ability to fix nitrogen, but it is relatively short-lived (up to 40 years). The tree is deciduous in cold areas and prone to frost damage. It has a long taproot, but its roots are invasive; planting near paving/foundations should be avoided. Propagation is by seed soaked in hot water and left overnight; young trees are best fertilised with compost and bonemeal. A. karroo grows in most free-draining soil types, in full sun or partial shade. Drought-tolerant, the root zone should be deep-watered every one to two months during the summer. A beautiful patio-sized tree for the garden, its bright yellow flowers against dark green foliage and reddish-brown bark are highly attractive. Useful for erosion control, as a windbreak, thorny informal hedge, or barrier. Maintenance includes careful training of the leader, gradual removal of side branches until all are above head height, so that the long thorns are no problem, and also spring pruning of dead wood. The tree is prone to attack by mealybugs.

Algarrobo Mesquite, Chilean Mesquite

The Chilean Mesquite is a medium-sized tree, native to Chile, where it grows under extreme conditions, and for this reason it is also suitable for planting in Arriyadh, although it is not nearly as often seen as its relative, P. juliflora. Symmetrical, fast growing to 9 metres high and an equal spread, it has an open crown, is more upright than juliflora and has bright-green, fine-textured foliage with widely spaced leaflets. The twisted trunk has smooth bark when young, becoming darker and rough with age; some young specimens have very large white thorns. The flowers are moderately showy, cream- to yellow-coloured. Catkin flowers bloom in spring or early summer, followed by slightly curved pods 12 cm long. Trees require full sun, and reflected heat; they are frost-resistant, but will lose leaves with sharp cold and keep leaves in warmer winters. This species can grow in most extreme conditions such as saline soils and drought; little to no supplemental water after establishment, but occasional deep irrigation, will improve its appearance. It adapts to most soils with good drainage. Propagation is by seed or cuttings. Maintenance requirements are high owing to pod, flower and leaf litter, and pruning to remove crossing and sprouting lower, thorny branches. P. chilensis is a good choice as a shady tree for a garden or natural landscape. P. cineraria, almost native to the edge of the Ruba Al-Khali and Oman, is a further Prosopis species which could have potential for use in Arriyadh.

Argentine Mesquite

The Argentine Mesquite is a semi-evergreen, upright, vase-shaped tree with a broad canopy, which grows to 10 m in height and spread. P. alba together with P. chilensis and P. juliflora were introduced into the Kingdom and Gulf States as roadside trees, and for other ornamental purposes. This handsome tree is well adapted to arid habitats, and has been seen to grow well in Arriyadh. Its short trunk has a thin, greyish-brown bark. Delicate, bluish-green, bipinnate leaves with paired leaflets are more closely spaced than those of other Prosopis species. The tiny flowers, which attract bees, are yellowish catkins which bloom in spring; fruit pods are up to 20 cm long and generally highly curved. Stems and trunks sometimes bear large thorns in a zigzag fashion; the bark is dark and rough. Trees require full sun and reflected heat, and will grow in poor, alkaline, saline soils and have deep roots reaching the water table. Requiring no irrigation after establishment, periodic deep watering improves appearance. They cannot withstand a series of heavy frosts. Propagation is by seed and cuttings. Maintenance requirements are high, owing to pod, flower and leaf litter, and the plants need training, secure staking and pruning in late summer for a strong structure. P. alba has landscape value as a small shade tree, in street medians, buffer zones, screens and windbreaks, and is effective in parks, but is not suitable for lawns. Possible problems and other cultural requirements are the same as for P. juliflora.

Loquat

Eriobotrya, commonly known as Loquat, is an evergreen shrub or small tree with a compact, rounded structure that reaches a height of between 3 and 8 metres. It is indigenous to Central China and South Japan, and seen in Arriyadh only in sheltered gardens and farms. The bark and young branches are woolly and the large, deep-veined and saw-toothed leaves are glossy, dark green on top and rusty underneath; they are elliptically shaped and up to 30 cm long. Clusters of small, white, rose-like flowers appear at the branch endings in panicles in autumn and winter, exuding a scent of vanilla. The small, edible, round fruit is deep-yellow in colour, and sweet in flavour. The large seed can be squeezed out of the fleshy fruit. Loquat is deep rooting and likes well-drained, but moist soil, and is nevertheless quite drought-tolerant. Growth rate and salt tolerance are moderate. E. japonica can be propagated by seed or cuttings. It is an appealing, small tree for a protected, private garden or patio or a large container, because of its attractive foliage, flowers and fruit. Best planted in wind-sheltered locations, Loquat will make an excellent specimen, dominant or edging plant in a park, too, if sheltered. It requires a rich dressing of fertiliser in spring, and is susceptible to fireblight, root fungus and mealybugs. Maintenance is moderate and pruning is required from time to time to improve the tree’s shape and to thin out the interior branches, to allow sunlight to reach inside. In this way, fruit-bearing will be increased.

Apple-Ring Acacia, Ana Tree, harraz

The Ana Tree, formerly known as Acacia albida, and in Arabic as harraz, is native to Africa and introduced into the Middle East, India and Pakistan. It is a large, very thorny, deciduous tree reaching 30 metres in height in its native habitats on floodplains and dry watercourses. A fast-growing tree with a thick trunk and zigzag branching habit, the pale grey-green leaves are borne on whitish-grey, smooth stems and branches when young, which become grey and rough when older. The straight, whitish thorns are up to 40 mm long. The bark is grey, and fissured when old. Scented, pale cream-coloured flowers in long spikes occur from March to September, and are followed by large, unusually twisted, fruit pods, bright orange in colour. F. albida has a deep tap root, making it very drought-resistant, and it will grow in waterlogged soils and withstand occasional frost. For propagation, its seeds should first be treated with boiling water overnight before sowing. Young plants develop long tap roots and should be planted in the ground quickly. The tree is particularly useful in nitrogen fixation and erosion control, and is highly valued in agroforestry. It also has medicinal properties in the treatment of infections. Susceptible to mealybugs and scale, it can be treated with systemic insecticides. Large areas of the Sahara in Niger have been re-afforested with the Ana Tree, with great success. With its white twigs and thorns, it is an interesting specimen tree in a park or large garden with only low maintenance requirements.

Grey-haired Acacia, sant al waraqi

A. gerrardii is a variable species. The variety iraquensis (sant al waraqi) has a rough, spiny trunk and finely fissured, dark-coloured bark, which does not peel off in strips like that of the whitish bark of A. gerrardii var. najdensis, (sant al najdi). The seeds of iraquensis are held in sickle-shaped, flat pods which are beige-coloured, long and straight, and covered by fine, grey hairs. Those of najdensis are strongly curled, almost circular pods, and a much darker brown. A. gerrardii has a distribution in the northern part of the Arriyadh region and Saudi Arabia and is usually found in depressions and watercourses. A small tree with ascending branches and a flattened crown. It has a long, straight and single stem with a reddish bark. Young, strong branches are densely covered with grey velvety hairs. Numerous thorns are arranged in pairs and white in colour, while mature trunks are almost thorn-free. Singular, round, creamy-white, sweet-scented flowers appear from October to February. During a very cold winter, the tree is deciduous. Propagated by seed, A. gerrardii is fast-growing, hardy to about –10 °C, and drought-resistant. It will become a spreading shade tree, when watered frequently. Its winter flowers make the tree an attractive species for arid landscape design in both intensive and extensive landscape situations. It is suitable for most gardens with a native look, and valuable for revegetation schemes, and roadside planting. Little maintenance is required once trained well into a straight leader.

Blue Palo Verde

Native to the Sonoran and Mojave deserts of Arizona and California, Cercidium species are not only some of the most drought-tolerant of trees, but are also outstanding flowerers, deserving to be used much more prominently in Arriyadh. Not often planted in Saudi Arabia, C. floridum is nearly always mistaken for the very common Parkinsonia aculeata (Jerusalem Thorn), which in many ways is quite similar. However, with careful observation, it is noticeable that the smooth, bright-green bark of Cercidium is different to that of Parkinsonia. C. floridum is to be found in the central median of the King Khalid International Airport highway. This slow-growing tree reaches a height of 9 metres with equal spread, and is deciduous in dry and cold spells. When it loses its fine-textured foliage, the dense, green and spiny twigs give it the appearance of an evergreen. Fragrant masses of bright-yellow, pea-shaped flowers are a wonderful sight covering the whole tree in spring. They are followed by pods. The blue palo verde withstands great heat and intense sun; drought-tolerant once established, deep watering on a regular basis during the growing season encourages faster growth and spectacular flower displays. It tolerates alkaline soils and is moderately frost-tolerant. It is propagated by seed, which germinates readily once the hard seed coat is scarified. Blue Palo verde is a beautiful, small shade tree providing stunning spring colour. It is useful for road and footpath planting, and as an accent in gardens, courtyards and parks.

Apple Blossom Shower, khiyar baladi

The Apple Blossom Shower, or khiyar baladi in Arabic, is a deciduous, flat-topped tree with pinnate leaves. It grows comparatively quickly to 15 metres or more, and has a canopy of a similar size. The branches droop gracefully and may even sweep the ground. Oblong leaflets are some 5 cm long and arranged even-pinnate on midribs of up to 70 cm in length. It is not easy to trace back the natural area of distribution, because this tree has long been planted for ornamental purposes. Java and Sumatra would appear to be their native islands. Not often seen in Arriyadh, where frosts may lead to severe damage, their natural habitat ranges from evergreen or deciduous forests to savannah-like habitats. For a period of about six weeks, showy pink, slightly fragrant flowers appear on racemes in spring while the twigs are still bare. Numerous flat seeds mature in pods that may reach 60 cm in length. This tree may naturalise where its requirements are met. Propagation is common by scarified seeds. They may also be used for medicinal purposes as a laxative, but can also cause emesis. Its reddish wood may serve for construction purposes. A number of subspecies are cultivated in tropical climates. Cassia javanica ssp. agnes is a highly ornamental subspecies with larger flowers. It is suitable for urban areas and may grow along roads as long as the pods do not litter trafficked areas. Wind exposure may damage the brittle branches. Chlorosis often occurs as a result of iron deficiency. Pruning is best done at the end of spring, after flowering.

Horseradish tree

The Drumstick or Horseradish Tree is an erect, fast-growing tree with open branches and a graceful appearance reaching up to 10 metres in height. Native to India, it is characterised by its thick, dark corky grey bark, delicate foliage and beautiful, fragrant flowers. The distinctive, bipinnate leaves up to 40 cm long have widely spaced, oval, clear green leaflets on short stalks. Attractive whitish-yellow, highly scented flowers are borne in loose clusters covering the whole tree in spring and early autumn. The fruit, up to 50 cm long, is a bright-green, ridged pod containing many seeds, which are a popular ingredient in curries. The tree grows best on a dry sandy soil and has a high drought resistance. In Arriyadh, it requires regular irrigation and a sheltered microclimate with a humid atmosphere. Propagation is from seed and cuttings. The Horseradish Tree is useful in many ways: its name is derived from the roots, which taste like horseradish, and the seeds yield oil for machinery, salad oil and soaps. The bark contains a coarse fibre for making mats, paper and cordage. The branches are used for fodder. M. oleifera makes an ideal shade tree for courtyards, patios and small gardens. Undemanding, it requires careful pruning: branches can be brittle and are planted as a living fence. It is not susceptible to pests or diseases. A wild shrub form growing in rocky wadi sides is M. peregrina (al ban in Arabic): up to 3 metres high, it has profuse flowers, is drought-tolerant and has good potential for garden cultivation.

Yellow Poinciana, Rusty Shieldbearer, Copper Pod

Bearing names such as Yellow Poinciana, Rusty Shieldbearer and Copper Pod, this is a showy, flowering tree, native to tropical Asia and Australia, and introduced to the Arabian peninsula. Not often seen in Arriyadh, where it may lose its leaves during a long dry period, the leaves reappearing quickly with the flowers. It grows rapidly to 20 metres high and 10 metres wide, and has an umbrella-like crown with fuzzy, rusty-red twigs. The rich green, bipinnate leaves are about 60 cm long with oval leaflets. Bold, yellow, nocturnally fragrant flowers, with crinkled petals, each with a brown spot, are borne on spectacular, upright racemes about 45 cm long, blanketing the tops of trees. Large bunches of the copper-coloured fruit, containing flattened, oblong seeds, are attractive at first, but later look untidy because they remain on the tree for months. P. pterocarpum requires light shade to full sun, and cannot tolerate heavy frost. It is very salt-tolerant, preferring moist, well-drained, sandy soil. Being drought-resistant, irrigation requirements are moderate. Propagation is by seed, which needs to be scarified. Yellow Poinciana is an excellent shade, street tree and a specimen tree, if plenty of space is available. It needs regular pruning, when young, to keep the tree dense and in shape. Care should be taken not to plant it too close to structures and hard paving, since the trees have shallow root systems. Generally pest- and disease-free, this is a low-maintenance tree, which may create a leaf litter problem, if not kept neat.

Salt Wattle

This tall shrub or tree, recently introduced in ArArriyadh, is native to Australia, where it grows along watercourses or in swales and drainage lines in hilly country on heavy, sometimes saline, alkaline soils. Such topographical situations are similar to those of the shallow wadis and rowdahs of the Arriyadh region, where water collects after winter rains. In fact, the tree can withstand dry periods of up to nine months. Acacia ampliceps is a fast-growing but relatively short-lived species with a life span of usually not more than 50 years. It has a spreading habit with canopy stems branching from the ground. Sometimes, the plant is almost prostrate. Pendulous branchlets have thin, light-green, lanceolate phyllodes. The flowers are in white to cream, with globose heads. For a while, there was a confusion of this species with A. salicina. Highly tolerant to salinity, the tree is, however, frost-sensitive. The foliage can also be susceptible to insect attack. Propagation is by seed. Where coppicing is necessary as a maintenance measure, the tree responds well. For landscaping purposes, the tree’s thick foliage makes it an ideal plant for screening, while the prostrate form makes for a good groundcover shrub. Unfortunately, it sends up many suckers, limiting its use near a lawn, for example. Regional studies have shown that A. ampliceps has great potential for use in the reclamation of sabkah areas, as a low windbreak, in dune rehabilitation and erosion control projects. It is also suitable as fodder in arid areas.

Giant Lemon, trunj

This variety of the lemon tree is also known locally as trunj, and is probably the hybrid named 'Ponderosa': it is often seen on farms in the Riyadh region. It is, however, relatively frost-tender and the trees may be damaged by drying winds or prolonged cold. Bearing highly ornamental fruit of extraordinary size of more than 20 cm, twigs may be bent down by the weight of many huge lemons. The tree grows fast up to 3 metres high, bears fruit early and has an angular shape with large leaves. It can be trained on a trellis to stabilise the branches and to prevent damage. Young plants are delicate and cannot compete with weeds. 'Trunj' requires a well-drained, sandy and fertile soil, with regular watering until established. Complete NPK fertilisers should be applied in early spring. Citrus trees have the attractive tropical feature of producing flowers and fruit at the same time. The fruit does not have any particular commercial value, but the non-acid lemons have a thick, bumpy rind that can be used for producing jam. The rind is low in essential oils, but gives off an aromatic scent and is sometimes candied or preserved in brine. Pruning should be limited to removing water sprouts, usually the result of severe cutting back of the branches of older trees. Most of these shoots are short-lived anyway and leave unsightly sticks on the branches. Deadwood might be provoked by prolonged drought or waterlogging. Like all citrus, the trees suffer from attacks by mealybugs, aphids and often have mildew.

Nile tamarisk, athel, tarfah

Tamarix nilotica is known as Nile Tamarisk or Manna Tamarisk, in Arabic athel, abal or tarfa. The name Manna comes from the fact that insects would suck the sap of these Tamarisks, and then excrete the honeydew-like substance as part of their metabolism. These sweet Manna balls were used by the Bedouins as nourishment. They also had a medicinal use as an anti-inflammatory and antibacterial agent against throat and gum inflammation. A shrub or small tree, its area of distribution lies in the Arabian peninsula and northern Africa. The preferred locations reach from Mediterranean wood- or shrublands up to extreme deserts. The slow, irregularly growing tree reaches a height of 8 metres. It is often multi-stemmed, and the foliage is grey-green. The leaves are squamate. The purple flowers stay in panicles together. These panicles are usually 10 cm long. Flowering lasts very long. The fruits are capsules. Propagation is by direct seeding and by cuttings. Tamarix nilotica can withstand high salinity. It has no special requirements in relation to soil or irrigation. It is adapted to the desert, with its hot winds, droughts and heat. The Manna Tamarisk is useful in open country as a coloniser, bank stabiliser and for environmental consolidation because of its invasive roots. The small tree is attractive in groups or massed planting. Woodland edges, pond or stream edges, as in its natural habitats, will be the best recommendation for its use in landscape design, for example in Wadi Hanifah or the Al Hair Lake Area.

Arjuna Tree

The Arjuna Tree, native to India, is a tall, deciduous, tree up to 25 m high, often with a buttressed trunk, the bark of which is grey or pinkish-green, smooth and peels off in thin strips. Found growing in several locations in Arriyadh (e.g. behind the Hotels Intercontinental and Khozama), it is not readily identifiable for most people. It is also very similar to T. elliptica. Arjuna has a wide crown with drooping branches. Its leaves are hard, simple, opposite, and elliptical, up to 9 cm long, often with crenulated edges: trees are sometimes leafless before late-spring flowering and new leaves appear in late winter. The small, cup-shaped, creamy or greenish-white and strongly fragrant flowers are borne on small terminal spikes up to 13 cm long. The dark brown, oblong, woody fruits with stiff, narrow, striated wings take nearly a year to ripen. Initially a slow-growing tree, the Arjuna has a shallow root system. In its native habitat, T. arjuna grows on most soils in ravines or in dry watercourses, becoming very tall on fertile alluvial loam. Tolerant to salinity and drought, regular irrigation is, however, required in Arriyadh. It will withstand cold winters, but is sensitive to hard frosts. Propagation is by seed, root suckers, and air-layering. T. arjuna is suitable for planting on saline, alkaline soils and deep ravines, and is a useful park tree and background tree in a large garden. Apart from tidying leaf litter and occasional deep watering to improve appearance, little maintenance is necessary.

Arabian Acacia, Babul, Gum Arabic Tree, garad, sant al arabi

Usually referred to by its synonym, Acacia arabica or sant al arabi, owing to its occurence on the Arabian Peninsula. A. nilotica var. tomentosa occurs in Saudi Arabia in wadi habitats and rowdahs on sandy and alluvial soils. Single-stemmed, this medium-sized tree with its flattened or rounded crown is easily identified by the long, flat, straight, velvety-grey fruits with up to 12 constricted round seeds, which hang like peas in a pod. Young branchlets are densely white-tomentose. The tree typically has a black bark with cracks exposing a red inner layer, which exudes a sticky, reddish resin, well known as gum arabic. The long spines in pairs are sharp, while the leaves are only quite small: fragrant, fluffy yellow flowers appear during winter until spring. Very drought- and salt-tolerant, A. nilotica is unfortunately susceptible to freezing temperatures. All parts of the tree have medicinal properties; its twigs are valued as chewsticks. Tender pods and shoots are used as forage for camels, sheep and goats. Propagated by seed, which may require scarification, direct seeding is common practice in afforestation schemes. It grows rapidly in full sun, in dry, well-drained sandy or silty soils. After establishment, irrigation can be reduced, whereby occasional deep watering will stimulate growth and deep roots. Planted as a specimen tree or in groups in a desert or extensive landscape situation, the tree, with sufficient space, makes a beautiful silhouette. Unless frequently pruned to preserve its shape, the tree becomes leggy.

Neem Tree, neem, shereesh

The Neem tree belongs to the mahogany family. It originates from Myanmar, but was dispersed to many tropical countries. Usually, it grows to about 15 metres in height and 10 metres diameter. Its bark is deeply fissured and dark grey in colour. Alternate leaves are pinnate, up to 40 cm long and light green; leaflets are ovate with a serrated margin. In mild winters, they may last until spring, but generally this tree sheds its foliage in Arriyadh’s climate. A. indica struggles somewhat in Arriyadh’s extremely dry air and rarely achieves the beauty of Neem trees growing in Jeddah, for example. White or pale-yellow flowers appear in spring and are slightly fragrant. Self-incompatibility hinders isolated trees to grow fruit. They may develop into round drupes that turn yellow or purple when ripe. Fruits are eaten raw or processed. Birds eat them and in this way may disperse the seeds. The tree has achieved an almost pan-tropical distribution owing to its adaptability on the one hand and its various qualities on the other. Mature Neems tolerate some frost and tolerate full sun. Any soil is tolerated, unless it is waterlogged. Neem trees are used to control erosion and to fix dunes. They are easily raised from seeds after the pulp has been washed off. Vegetative propagation is possible, such as by hardwood cuttings. Branches are easily reproduced after hard pruning. The rough wood repels insects, and resists even termites. Neem glue and neem tea are therefore ideal replacements for insecticides. Neem oil is extracted from the kernels.

Bottle Tree, boudret al afreet

This Brachychiton is more drought-resistant than B. acerifolius. It tolerates full sun and a hot desert climate, just like in its native country, the semi-arid inland of eastern Australia. Trees are found growing there amongst rocks of granite or limestone, but also thriving in deep soil. Narrow and pyramidal when young, the plant’s name refers to the widened base of the trunk which is an adaptation for storing water during prolonged periods without rainfall. On the other hand, it responds well to irrigation by growing faster. It may reach 10 metres easily, while 20 metres are to be expected only in its native environment. Known in Arabic as boudret al afreet, it is often seen in Arriyadh, where the shiny, bright-green fluttering leaves provide a lush effect. The green bark is smooth and attractive. They allow distinguishing two subspecies; Brachychiton populneus ssp. populneus has reduced lateral lobes, while three or five lobes create the palmate leaf of ssp. trilobus. Both subspecies have flowers in light yellow with purple centre appearing in spring. Cultivars may also flower in pink or red. Stagnant water is one factor to avoid definitely, hence soil should drain well. This tree blends in well in desert landscapes, creating dense shade. Not many trees do as well in lawn areas as the Bottle Tree. The root zone should be soaked thoroughly every couple of months in summer. It survives in an urban microclimate, but the littering fruit and annoying itchy hairs limit it to area where the dry pods do not affect passers-by.

Carob Tree, St. John’s Bread, carob, qarmatt

This evergreen tree, known in Arabic as carob and English as St. John’s Bread, used to be native to the Arabian Peninsula as a wild variety. The Egyptians cultivated it 4,000 years ago. Nowadays, it can be found in the Mediterranean and in southern Europe. It is, however, only seldom seen in the Arriyadh region, sometimes on farms or in sheltered private gardens, and is probably more suitable for a coastal setting. Carob is a tall shrub or tree which grows up to 10 metres high with an equal spread, and has a dense crown. It is slow-growing and often multi-stemmed. There are both male and female trees (the pods appear on the latter). The dark-green leaves are pinnate with up to ten glossy oval leaflets. The flowers appear in small clusters in late summer on pale-yellow racemes directly on the stem and branches. The fruit is more imposing, and gives the tree its name. Huge, green and later dark-brown elongated pods hang all over the tree. C. siliqua grows on sandy, limey soil with good drainage and is highly salt-tolerant. It does require some humidity, but once established it is relatively drought-tolerant, because of its deep tap roots. It is sensitive to frost. In ancient times, people in the Middle East used to weigh gold and gems against the seeds of the carob tree, which was known in Greece as keration. C. siliqua is propagated by seed and cuttings. Ceratonia is a beautiful specimen shade tree for parks and private gardens. The root zone should be thoroughly soaked once per month. All parts of the tree create litter.

Floss-Silk Tree

Floss-Silk Trees are large, winter-deciduous trees, native to subtropical South America, and tolerate some frost to about –7°C, when mature. Young trees are more sensitive to cold. They grow to about 18 metres high and about 9 metres wide with horizontal but gnarled branches that shed the palmate foliage in autumn. They are composed of five to seven oval leaflets. After the leaves have fallen, showy pink flowers with curved petals are borne with up to 16 cm in diameter. They are pollinated by butterflies and develop fruits that are reminiscent of small, brown avocados with woody rind. These split open when ripe to release black seeds that are muffled by white, cottony fibres. Like those of Silk Cotton Trees (Bombax ceiba), they are used for stuffing pillows. An edible oil may be obtained from the bean-sized seeds. The dull-green trunk is covered with grey, conical spines, giving it a decorative feature. It becomes bulky with age in its lower third, and eventually achieves the shape of a bottle. The green bark performs photosynthesis before it turns light grey when old. Established trees do well in full sun and require occasional soaking in summer. Good drainage is important and the soil should be fertile. C. speciosa is a magnificent specimen tree for parks and courtyards, where it may be protected from frosts. Its interesting trunk should be admired from close by, and not hidden by shrubs. Maintenance is minimal with occasional pruning every few years. Floss-Silk Trees are best propagated by seeds.

Rusty Fig, Rustyleaf Fig

The Rusty Fig, native to Australia, is a broad, densely shading, evergreen tree that may reach 30 metres in height, spreading up to 15 metres when mature, making huge specimen trees. It also often makes an attractive multi-trunked tree. Rather slow-growing, a buttressed trunk is eventually formed, which can reach 1.5 metres in diameter: the bark has a yellow-brown colour. Its ovate to oval-shaped leaves are 6–10 cm long: the brown, short fuzz and rusty colour of the undersides of the leaves give the tree its name. The inedible figs ripen from yellow to red. In humid climates, the lower branches of the tree form aerial roots. F. rubiginosa tolerates many types of soil, even where compacted and poorly draining, and will grow well under arid conditions. It prefers full sun, but also grows in partial shade; regular irrigation is required in summer, less in winter. Once established, it can withstand short periods of drought and frosts, and withstands more cold in Arriyadh than other Ficus species. It is easily propagated by cuttings or aerial layering. Scale insect may become a problem. F. rubiginosa is an excellent ornamental tree; however, it can be planted only in very large private gardens, owing to its aggressive root system, which can damage underground pipes and foundations. It makes a very good shade tree in parks and is tolerant of urban microclimates. It is also a valuable plant for wildlife. Trees should be carefully pruned from the outset to create a good structure: by removing some branches an open form can be achieved.

Egyptian Rattle Pod, nowm, sasban

In northeast Africa, this shrub may be encountered in dry riverbeds and swamp banks along streams. The Egyptian Rattle Pod adapts to its environment by growing shrubby, as a multi-trunked tree or as specimen with a single stem. Mature plants range between 2 and 8 metres in size. Its deciduous foliage is pinnately compound, some 18 cm long, with many pairs of oblong leaflets which measure about 2 cm in length. Attractive bright-yellow flowers are borne in racemes mainly in spring, when humidity and warmth indicate good conditions both for pollinators and for the shrub. In its tropical homelands, this plant produces flowers when the rain periods start. This species flowers in deep yellow, white and in intermediate shades. After the pea-shaped blossoms are pollinated, long, narrow pods develop containing up to 50 seeds each. As with other leguminous plants, the Egyptian Rattle Pods improve the soil by fixing nitrogen and adding humus. Their foliage is used as green manure and as forage for livestock. For its attractiveness and multiple uses, this species has long been grown beyond its native habitats, spreading widely in Africa and Asia. It is resistant to stagnant water and poor soil conditions including alkalinity and high salt content. Drought will lead to dormancy. Sowing is the most appropriate method of propagation, but the hard, bean-like seeds need some encouragement through scarification. Since it is widely adaptable and tolerant of adverse conditions, this shrub can be integrated into almost any landscape situation.

Yellow Jacaranda, Pride of Bolivia, Rosewood

Yellow Jacarandas are semideciduous trees from Bolivia, where they reach a height of 35 metres. In cultivation, they often stagnate at 10 metres, forming a flat crown that widens to an umbrella-like shape with age to about 10 metres in width. The foliage is pinnately compound and consists of numerous ovate, fresh-green leaflets. From late spring to early summer, clusters with golden, pea-shaped flowers are borne abundantly. They create a dense carpet when they drop, which should be borne in mind when the tree is used in parks or large gardens as an eye-catcher. They form winged pods. As a tropical native, this tree goes dormant according to circumstances rather than by season. In Arriyadh, however, the leaves are shed for a brief period in late winter to regrow a few weeks later. Prolonged drought may induce the same procedure in summer, which should be prevented by moderate watering in well-drained soil. The tree may be exposed to full sun, takes salinity and tolerates light frosts. Alkaline soils should be improved by adding compost and applying acidic fertilisers. Young trees should be pruned and staked initially to form a straight trunk. Yellow Jacarandas adapt to variable conditions and tend to escape from cultivation in semi-humid climates. They are easily propagated by seed, and require only a minimum of care once established. As shade trees, they are ideal where their dropped flowers and seed packets do not create a nuisance. Consideration should also be given to the aggressive roots, which may lift pavements or asphalt.
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Saltbush, Orache, raghal

There are some ten species of Atriplex growing presently in Saudi Arabia: seven are native (Atriplex coriacea, A. dimorphostegia, A. farinosa, A. glauca, A. halimus, A. leucoclada and A. tatarica), and three have been introduced and cultivated (A. canescens, A. semibaccata and A. suberecta). Atriplex is a halophytic plant which has developed various strategies to adapt to saline environments with excessively high salt content in the soil. Originating in the Mediterranean basin, A. leucoclada, known in Arabic as raghal, is a low perennial shrub with upright grey stems and triangular leaves and densely clustered, bell-shaped flowers and fruits, which appear on spikes in spring. The shrub grows in many different habitats, but it usually occurs on sabkah, coastal and inland salt marshes with a high accumulation of salts, and occasionally on silty soils. Frost-tolerant with a medium growth rate, the species is polymorphic, meaning that the shape and size of its leaves may vary according to season and habitat. A. leucoclada is an important species for agricultural use in arid regions. Atriplex species can be planted for soil desalination, and CO2 sequestration. Studies have shown that Atriplex is able to survive sodium chloride salinity up to more than 100% of seawater salinity, indicating that A. leucoclada can be grown productively at moderate salinity. It is a useful plant for desert and extensive landscape schemes as a groundcover, occasionally requiring watering and maintenance to improve its appearance.

Desert Germander, aihan, qasba’a

Teucrium oliverianum has the common Arabic name aihan or qasba’a. The English common name is Germander. It is native on the Arabian peninsula. Aihan is a subshrub and herb with long, erect branches. It reaches a height between 40 cm and 70 cm, growing like a dwarf shrub. The foliage is evergreen to semi-evergreen. The leaves are green on the top and olive-green underneath. The triangular leaves are entire and oppositely arranged. The bloom appears in spring, with beautiful blue-violet Lamiaceae flowers with long stamens. That and its shape make T. oliverianum an attractive ornamental plant. The plant develops nutlets as fruits. Propagation is by direct sowing. Aihan does not like salinity, but in all other characteristics it is completely well adapted to desert conditions and appreciates sandy, silty or rocky soils. Teucrium has no special irrigation requirements, although irrigation would optimise growth and flowering. Pruning will densify the shape. Teucrium can be found in Arriyadh and its surroundings, especially adjacent to dry run-offs. It is really eye-catching, and cannot be ignored. The abovementioned attributes make the Germander very valuable for landscape design in Arriyadh. It is recommended for use as a ground cover, massed planting, as borders or in rock gardens. This bee-attracting plant can be used in private gardens, or it has potential as an ornamental plant in the urban design. For open country, it should be used for the rehabilitation of natural plant cover.

Bladder Dock, Sorrel, humeidh

Rumex vesicarius is known in Arabic as humeidh. This annual herb is native to the Arabian peninsula and can be found throughout Saudi Arabia. The annual is fast growing and reaches 50 cm in height and width. The shape is that of a dwarf shrub, regular and upright. The fleshy leaves are green ovate-triangular. The leaves are edible. The pale-red, raceme-like flowers appear in spring. In full sun, the winged bloom becomes dark red. The 5-mm seeds grow inside the winged flower. Propagation can be done by seeds. Humeidh grows in silty, loamy soil, and has a lateral root system. Branches are fragile and may need wind protection. It is quite tolerant to salinity and needs moist soil. After rainfall in late winter and spring, it is very widespread in Arriyadh and the surrounding area, lending desert landscapes a soft reddish bloom. On the escarpment of the Tuwaiq Palace in the Diplomatic Quarter, it has spread by self-seeding, and provides a very attractive sight in the spring every year, especially after rains. With increasing heat, Rumex will vanish during summer until the following winter or spring. For landscape design purposes, Rumex is useful in open country as a coloniser and slope stabiliser. Because it is native in the Kingdom, it is valuable for the rehabilitation of natural plant cover. In seed mixtures, it will support natural soil preparations in its pioneering function. Rumex is valuable as a groundcover and bedding plant in urban situations, and has potential for use as an annual for street planting in winter.

Indian Ginseng, Winter Cherry, sum al far

Withania somnifera has several common names such as Indian Ginseng, Winter Cherry and, in Arabic, sum al far. It is a perennial or better shrub that is distributed within India, Africa and the entire Arabian peninsula. In Indian Ayurveda medicine, it is a popular remedy, and the name means something similar to sweaty horse, based on the flavour of the roots. Sum al-far grows up to a height of 150 cm and attains 1 metre in width. It is fast growing and develops a conical dense crown. The deciduous foliage is green with oppositely arranged leaves. The leaves are 10 cm in size, and ovate. The bloom is very small, and whitish-green. The flowers appear in summer. The fruits are roundish berries, 5 mm in size, with a bright-red colour. Propagation is by direct sowing. Soil requirements are low, with the plant growing on sandy or silty soil. W. somnifera can withstand temporary droughts, but also grows in moist soil. Irrigation is not required after establishment, but growth will be improved with some watering. Salinity should not be greater than medium. Sum al far is not very hardy, which means that it will die back in strong winters. In Arriyadh, it can be found in the Wadi Hanifah lake area, where it grows next to the shore in sheltered situations with some shade. For landscape design purposes, it can be recommended for situations such as a coloniser in open country as groundcover and as a small hedge. However, with its fresh dark green foliage, it will also be pleasing in sheltered private gardens and courtyards.

Apple-Ring Acacia, Ana Tree, harraz

The Ana Tree, formerly known as Acacia albida, and in Arabic as harraz, is native to Africa and introduced into the Middle East, India and Pakistan. It is a large, very thorny, deciduous tree reaching 30 metres in height in its native habitats on floodplains and dry watercourses. A fast-growing tree with a thick trunk and zigzag branching habit, the pale grey-green leaves are borne on whitish-grey, smooth stems and branches when young, which become grey and rough when older. The straight, whitish thorns are up to 40 mm long. The bark is grey, and fissured when old. Scented, pale cream-coloured flowers in long spikes occur from March to September, and are followed by large, unusually twisted, fruit pods, bright orange in colour. F. albida has a deep tap root, making it very drought-resistant, and it will grow in waterlogged soils and withstand occasional frost. For propagation, its seeds should first be treated with boiling water overnight before sowing. Young plants develop long tap roots and should be planted in the ground quickly. The tree is particularly useful in nitrogen fixation and erosion control, and is highly valued in agroforestry. It also has medicinal properties in the treatment of infections. Susceptible to mealybugs and scale, it can be treated with systemic insecticides. Large areas of the Sahara in Niger have been re-afforested with the Ana Tree, with great success. With its white twigs and thorns, it is an interesting specimen tree in a park or large garden with only low maintenance requirements.

Rhazya, harmel, hamad

Rhazya stricta has the common Arabic name of harmel. It is an evergreen shrub growing about 1 metre high. This native shrub is distributed over the Arabian Peninsula. The numerous branches lie close to the ground. The leaves are alternately arranged, lanceolate and about 10 cm long. The foliage is very dense and leathery. The plant is a member of the Apocynaceae, and is poisonous in all parts. But, it was used as remedy for sore throat and fever. The small, white, star-like flowers appear in summer. After flowering, the plant develops small pods with black seeds. Propagation is by seed. The plant is very well adapted to harsh desert conditions with its strong foliage, tap roots and high salt tolerance. It grows on sandy or silty soil. Rhazya stricta can frequently be found in Arriyadh and its surroundings. With its dark-green foliage, it is eye-catching and a welcome sight in the harsh sunlight of the desert landscape. After long droughts, it may look a little straggly, because some evergreen leaves will dry out and become brown. Even so, however, it can be recommended for use in landscape design in open situations as a coloniser, a bank and slope stabiliser and for environmental consolidation. It is valuable to restore natural plant cover. In inner-city locations with some irrigation, it will not dry out, and the foliage will remain green. Some pruning will be necessary. It can be considered for natural themes or in situations where other plants are struggling because of hard site conditions, e.g. roadside greening.

Calligonum, abal, arta

An almost leafless, evergreen shrub with many stiff, upright branches, this plant is widespread in the desert and arid zones of Saudi Arabia, where it is known in Arabic as abal or arta. It is characteristic of deep sand, has a very long tap root reaching down to the water table and helps to stabilise the surrounding dunes. It is often seen growing in a hummock with the sand collected around it: it also occurs in plains and wadis, and is cultivated around desert plantations as a windbreak. Its abundant, yellowish-white flowers appearing in spring are not only attractive, but also edible and have a sweet scent. Relatively high, its fragile twigs are slender, the leaves tiny and the pretty, red, oval fruit is covered with hairy spines. It is fast-growing on sandy and gravelly soils and rock, and is very hardy with a high salt tolerance. Important for grazing, it is browsed by camels. It features frequently in the folk medicine of the desert owing to its food value, high in sugar and nitrogen. It is used for gastric, ophthalmic and stomach problems, as well as for hair scenting and dying; the dried leaves and stems are used to treat toothache. Propagation is by seed or cuttings. The vertical structure of C. comosum is extremely interesting for landscape schemes, although with age the plant tends to fall over and become untidy. It is a useful plant for sand dune stabilisation, hedges, massed planting and in the foreline of afforestation. Maintenance is low, and in extensive landscape schemes the plant will look after itself.

Toothbrush Tree, Arak Tree, meswak, arak

Known in Arabic as meswak or arak, this is the shrub that provides the twigs used as a natural toothbrush. Native to the Hejaz and extremely well-adapted to arid conditions, meswak is widespread, salt-tolerant and very drought-resistant. It is found where groundwater is available, in wadis, in seasonally wet sites, and along drainage lines. S. persica is an evergreen, slow growing, small tree or shrub up to 6–7 m high with a crooked, many-branched trunk, and fissured, whitish bark. It has a wide crown of green, crooked branches, and the twigs have a pleasant fragrance. The elliptic to almost circular, rather fleshy leaves have a high salt content and are light to dark green. The small, greenish to yellowish flowers, borne in loose, slender-branched panicles are up to 10 cm long. The edible, spherical, fleshy fruit is 5–10 mm in diameter, bright red when ripe and has a sweet, aromatic taste. S. persica prefers sandy soils and areas with high groundwater. Drought-tolerant, deep irrigation in summer will serve to improve the shrub’s appearance. With its high salinity tolerance, it has great potential for reclaiming saline soils. Leaves make good fodder for livestock, since they have a high water content and are rich in minerals. Grown in plantations or hedges, S. persica coppices well and is excellent as a shelterbelt, windbreak and in sand dune reclamation. It is prone to some pests and diseases, e.g. Cistanche tubulosa, a root parasite, and also defoliating insects. S. persica is an excellent desert shrub, requiring no maintenance.

Taily Weed, kardhi, alandra

Fleawort, jisjas, sabat

Pulicaria crispa is indigenous to Saudi Arabia, and is distributed nearly all over the entire Arabian peninsula. However, it is distributed in Africa as well, where it can be found along the Sahel zone. In Africa, it is used as fodder plant and as a remedy. In the Sahara, an infusion for drinking is made from this aromatic plant. The resulting drink has a gingery taste. In Arabic, P. crispa is called jisjas or sabat. Jisjas is a fast-growing bushy, annual or perennial desert plant. It grows like a small dwarf shrub between 40 and 50 cm high, and with numerous branches emanating from the base. The foliage is a fresh olive-green. The alternately arranged and sessile leaves are pubescent. The flowers appear in spring in 8-mm yellow knobs with an aromatic scent. The fruits are 2-mm achenes with small hairy tufts. The roots are lateral and tap-rooted. Jisjas likes sandy and rocky locations and is highly salt-tolerant. This plant is a native, and very well adapted to harsh desert conditions. It can withstand hot winds, desiccation, heat and poor soils. Maintenance or irrigation is not necessary after planting out in the location. Propagation is by direct sowing or by cuttings, and probably by self-seeding. Pulicaria crispa is a very useful plant for the rehabilitation of natural plant cover. It can be used in seed mixtures for areas that should be recolonised, or for environmental consolidation. But in natural garden themes such as rock or steppe gardens, too, it will be effective as groundcover, grouped or massed planting.

Mignonette, dayl al kharouf

Reseda muricata is distributed on the Arabian peninsula and the Middle East. In Arabic, it is called dayl al kharouf. In Saudi Arabia, it can be found along the West Coast, Hejaz and on the East Coast up to the central regions. Reseda muricata is a perennial, biennial and in some regions only annual herb. It is a fairly fast-growing plant and looks like a dwarf shrub. It reaches a height of 40 cm and a spread of up to 50 cm. The lower leaves are entire lanceolate, while the upper leaves are ternate. The foliage is grey-green. Flowering begins in summer, with long yellow-whitish racemes about 10 cm long. The individual flowers are 4 mm in size. The fruits are capsules with serrated pits. The root system is lateral and deep. Propagation can be done by seeds. R. muricata is an indigenous plant and is very well adapted to harsh desert conditions. The herb is highly salt-tolerant. Maintenance requirements are very low after establishment, and irrigation will improve a good development of the plant. The use of dayl al kharouf in landscape design can be seen in the rehabilitation of natural plant cover, which means it can be considered for open country, as a coloniser or slope stabiliser, and for environmental consolidation. Reseda will grow as a groundcover and as grouped planting. And even for natural garden themes or parks like Wadi Hanifah, it will provide a pleasing display. In the extensive landscape surrounding Tuwaiq Palace in the Diplomatic Quarter, some specimens can be found which were distributed by self-seeding.

Arabian Acacia, Babul, Gum Arabic Tree, garad, sant al arabi

Usually referred to by its synonym, Acacia arabica or sant al arabi, owing to its occurence on the Arabian Peninsula. A. nilotica var. tomentosa occurs in Saudi Arabia in wadi habitats and rowdahs on sandy and alluvial soils. Single-stemmed, this medium-sized tree with its flattened or rounded crown is easily identified by the long, flat, straight, velvety-grey fruits with up to 12 constricted round seeds, which hang like peas in a pod. Young branchlets are densely white-tomentose. The tree typically has a black bark with cracks exposing a red inner layer, which exudes a sticky, reddish resin, well known as gum arabic. The long spines in pairs are sharp, while the leaves are only quite small: fragrant, fluffy yellow flowers appear during winter until spring. Very drought- and salt-tolerant, A. nilotica is unfortunately susceptible to freezing temperatures. All parts of the tree have medicinal properties; its twigs are valued as chewsticks. Tender pods and shoots are used as forage for camels, sheep and goats. Propagated by seed, which may require scarification, direct seeding is common practice in afforestation schemes. It grows rapidly in full sun, in dry, well-drained sandy or silty soils. After establishment, irrigation can be reduced, whereby occasional deep watering will stimulate growth and deep roots. Planted as a specimen tree or in groups in a desert or extensive landscape situation, the tree, with sufficient space, makes a beautiful silhouette. Unless frequently pruned to preserve its shape, the tree becomes leggy.

Felt Plant, ashar

The Calotropis or Felt Plant is known in Arabic as ashar. It is indigenous in Saudi Arabia, but is also native to southeast Asia and tropical Africa. The shrub can grow to between 3 and 5 metres high, and about the same width. The fact that it is poisonous (eye and skin contact should be avoided) means that it is not often planted ornamentally. However, C. procera is an interesting plant and wrongly maligned. With its bold foliage, the leaves are light silver-green on top and velvety underneath; they are large, fleshy and ovate. The flowers are grey on the outside and purple on the inside, in clustered axillary inflorescences. The impressive fruit is a large capsule, which opens to release dark seeds with silky hairs for distribution by the wind. These unusual attributes make the shrub valuable for landscape design. Bark, roots, leaves and flowers have long been used as remedies for numerous illnesses. C. procera can be propagated by seed or cuttings. The shrub has a tap root and it grows very well in sandy or silty desert conditions. The Felt Plant can tolerate high salinity and requires no irrigation once established. It is an attractive plant for natural garden themes, in rock or steppe gardens, and as a specimen making a silhouette against a wall or in group planting. It can be used in both open desert and urban areas. C. procera plays an important role in improving soil fertility, and also improves the water-retaining capacity of soil. Maintenance measures are necessary from time to time to improve its appearance.

Caper, lasaf, shaflah

Capparis spinosa has the common Arabic names shaflah, lasaf and malat. The shrub grows slowly to a height of 1 metre. It can often be seen in Arriyadh, particularly in cracks on the rocky edges of wadis. The branches with tiny spines in pairs grow from the ground and the 2–4 cm-small leaves are alternate; they have an ovate form and grey-green colour. The flowerbuds can be pickled to make capers, used in cooking. The beautiful flowers have four petals with stamens almost as long as the petals. The shrub is propagated by seed and cuttings. Capparis decidua has a number of common Arabic names including kerda and karir. The generic name is derived from the Arabic kapar. It is a slow-growing, small tree or shrub reaching a height of 5 metres and thrives on shallow, hard soils and stony outcrops. The Capparis is native to arid zones growing on rocky, clayey and silty soils in Africa, the Middle East and southern Asia. The branches seem to be leafless, because the leaves are only 2 mm in size. The bark turns silver-grey with time, and tiny spines in pairs are distributed over the branches. The flowers are bright red and conspicuous, and appear in small groups in spring and summer. In Africa, the fruits are used for camel fodder, where it is a very popular and useful plant in agroforestry. C. decidua grows on alkaline, sandy and gravelly soils. It is well adapted to drought, fire and frost. Both Capparis species are valuable for landscape design, afforestation and planting for erosion control. Low maintenance requirement.

Incienso, Brittlebush

Encelia, or Brittlebush, is a woody perennial or sub-shrub that is native to the Sonoran and Mojave deserts of northern Mexico and the southwestern USA. Seen up until now in only a few locations in Arriyadh – there is a flourishing enclave at Kasr Tuwaiq in the Diplomatic Quarter – it has great potential for widespread use. It grows from 60 to 90 cm high, and up to 150 cm wide. The evergreen leaves are silvery light grey. The bright yellow, daisy-like flowers are 2 cm in diameter, on long, thin stems above the foliage, as if they were floating above the shrub, which they cover in spring. The Brittlebush is completely adapted to desert conditions. Fast growing, especially after a wet winter, it needs nearly no irrigation once established. It will, however, die out after some years when very dry, only to make a comeback after self-seeding. It is tolerant of neither high salinity nor light frost, after which it will recover in spring. Encelia prefers full sun or partially sunny locations, and sandy or rocky soil with good drainage. Propagation can be done by seed or with cuttings. If self-seeding is not required, pruning of florescence after flowering is advisable, and trimming of branches in autumn will encourage dense growth. Attractive planting schemes with bright spots of colour can be created with E. farinosa as a small hedge, in grouped or massed planting in public open spaces and urban areas, as well as in park or street median planting and in pedestrian precincts and containers. It is an eye-catching plant in rock gardens.

Arabian Acacia, Babul, Gum Arabic Tree, garad, sant al arabi

Usually referred to by its synonym, Acacia arabica or sant al arabi, owing to its occurence on the Arabian Peninsula. A. nilotica var. tomentosa occurs in Saudi Arabia in wadi habitats and rowdahs on sandy and alluvial soils. Single-stemmed, this medium-sized tree with its flattened or rounded crown is easily identified by the long, flat, straight, velvety-grey fruits with up to 12 constricted round seeds, which hang like peas in a pod. Young branchlets are densely white-tomentose. The tree typically has a black bark with cracks exposing a red inner layer, which exudes a sticky, reddish resin, well known as gum arabic. The long spines in pairs are sharp, while the leaves are only quite small: fragrant, fluffy yellow flowers appear during winter until spring. Very drought- and salt-tolerant, A. nilotica is unfortunately susceptible to freezing temperatures. All parts of the tree have medicinal properties; its twigs are valued as chewsticks. Tender pods and shoots are used as forage for camels, sheep and goats. Propagated by seed, which may require scarification, direct seeding is common practice in afforestation schemes. It grows rapidly in full sun, in dry, well-drained sandy or silty soils. After establishment, irrigation can be reduced, whereby occasional deep watering will stimulate growth and deep roots. Planted as a specimen tree or in groups in a desert or extensive landscape situation, the tree, with sufficient space, makes a beautiful silhouette. Unless frequently pruned to preserve its shape, the tree becomes leggy.
  • Home Plant
  • Public Open Space
  • Cars Park
  • Pedestrian Precinct
  • Street Neighbour Planting
  • Swimming Pool Planting
  • Undergrowth
  • Open Country
  • Linear Planting
  • Pond
  • Rock Garden
  • Highway Planting
  • Massed Planting
  • Small Pond
  • Grove
  • Hillside Planting
  • Container Planting
  • Hillside Stabilization
  • Park Planting
  • Pond Edge
  • Stream Edge
  • Borders, Edges
  • Steppe Garden
  • Private Garden
  • Extensive Roof Garden
  • Roof Garden
  • Grove Planting
  • Hedge
  • Flowering Hedge
  • High Hedge
  • Low Hedge
  • Herb
  • Specimen
  • Tree Grille
  • Wadi Farm Garden
  • Swamp
  • Suitable For Commercial Use
  • Urban Area
  • Wadi Plant
  • Edging Plants
  • Rowda Plant

Sour Seville Orange

Sour Seville Oranges grow on these medium-sized trees that may develop to a maximum height of 10 metres, achieving a round crown. Northeast India, Bangladesh and Myanmar are the presumed homelands of this species. More than 1,000 years ago it was introduced into the Mediterranean and became so popular that its vernacular name honours the Spanish town of Seville. A vigorous grower in Arriyadh, the flowers produce an unsurpassed fragrance for several weeks in spring and are a welcome feature in many gardens. Thorny twigs bear shiny, dark-green leaves that release an aromatic scent when bruised. They measure about 12 × 7 cm. The white flowers are borne in spring and may be harvested to distil perfume. Some cultivars are grown for producing essential oils that is traded as ‘neroli oil’. Pollinated blossoms are followed by yellow-orange fruits that measure up to 8 cm across. The acidic, bitter pulp contains a large number of white seeds, and is enclosed by strongly aromatic peel. In orchards, the trees are spaced some 5 metres apart. The plant is tolerant of almost any kind of soil and is therefore sometimes used to bear graftings of more delicate citrus species. Heat is tolerated with appropriate soil humidity. Brief frosts do not harm healthy plants seriously, but soft leaves and non-lignified branches may be damaged. They take severe pruning and even recover from being coppiced. Sour Seville Oranges may be propagated by seeds for ornamental purposes and by grafting if cultivars are to retain certain characteristics.

Crown of Thorns

This succulent is native to Madagascar: it is often seen in Arriyadh in planters, usually with the intention of forming a barrier. Its edged stems are fleshy and able to store water while the foliage is not thickened. The obovate, dark-green leaves are found on new growth only. Male and female flowers are borne on the same plant, but both are inconspicuous. Nevertheless, a burst of colour is shown in spring by bright-red bracts. Sparse flowering appears during the other seasons too. It is attractive all year round for its strange appearance of thorny shoots that made it deserve the common name Crown of Thorns. Injured plants exude a milky, poisonous sap that can irritate skin. Pruning is not necessary, but is carried out to multiply the plant by cuttings. For this purpose, tips of 10 cm length are cut and placed in water until the sap stops flowing. Afterwards, they should be allowed to dry before being dipped in rooting hormone and placed in a mix of sand, perlite and humus. Excellent drainage is essential for mature plants too, since both waterlogging and overwatering by sprinklers kill the plant, especially in winter. Partial sun suits it best and extends the lifespan of the foliage. Drought is tolerated when the plants are established, but it also limits the endurance of the leaves. Slow-releasing fertilisers can be applied in spring to ensure a healthy appearance and an impressive floral display. Scale insects may infest plants on inappropriate sites. Frosts are not tolerated and immediately damage the foliage.

Garden Geranium, Zonal Geranium

Garden Geraniums are hybrids of various South African species. They are small, erect shrubs with herbaceous branches on a woody base reaching a maximum of about 90 cm in height and some 70 cm in width, depending on the cultivars. Evergreen, fleshy foliage covers the plant densely. The leaf edges are lobed, and the dull green upper side often shows a ring of purple or brown. Terminal clusters of striking flowers are available in a wide range of colours such as red, pink, lilac, violet, orange and white. A single inflorescence usually consists of five petals, but double flowers have many more. Although the flowering climax is in spring, flowers may be seen all year round, if spent clusters are cut off frequently both for a neat appearance and to induce the development of new buds. Garden Geraniums enjoy sunny locations, but will also do well in partial sun. The soil should drain well and offer enough nutrients for the plant’s vigorous growth. The plant takes some drought, but looks best if watered frequently. Light frosts are tolerated, but severe cold kills the entire plant. Pruning can be done at any time to replace the brittle stems by young shoots. Cuttings can be taken both in spring and in autumn. Sowing is a year-round alternative. These Geraniums are the ideal plants for pots, containers and beddings. They enhance mixed borders with splendid colours and suit both public and private sites. Regularly seen throughout the year in Arriyadh, they are most prominent when they are planted for a winter colour display.

Moses-in-the-cradle, Boat Lily

Boat Lilies are stout perennials with upright shoots up to about 40 cm in height. They grow in clumps with lush-green leaves some 30 cm long. From beneath, the lance-shaped foliage is burgundy-purple, creating an interesting contrast. Their origin is southern Mexico, Belize, Guatemala and the West Indies, where they flower all year round. In Arriyadh, small flowers appear whenever conditions are favourable, from boat-like cradles to eventually develop to round seeds. These easily germinate to form plenty of seedlings, ultimately creating dense mats. It is possible to prick these offspring or take cuttings from stems or leaves to propagate Boat Lilies. They grow readily in a wide range of soils, as long as these are well-drained, and they tolerate diverse light conditions ranging from full sun to partial shade. Although these perennials re-grow after nipped back by frost, exposed sites should be avoided. In time, the plants become dense clumps which can be used as border plants, areal cover, mass planting or group planting with a spacing of between 30 cm and 60 cm. They do well in containers and are popular house plants, but they are susceptible to the effects of stagnant water and prolonged drought. A cultivar named ‘Variegata’ has cream-coloured stripes and less vigour than the species. It must not be exposed to full sun, because the variegation will soon be sunburnt. Plants should be handled with care, especially if cut or bruised, since the sap may cause skin problems.

Benjamina, Weeping Fig

The Weeping Fig, native to southeast Asia, is a lushly tropical and elegant tree, more likely to be found as an indoor plant in Arriyadh than growing outdoors. Popular throughout the world in homes, offices and shopping malls, F. benjamina will withstand Arriyadh’s climate, but only when fully protected in a garden. In the past, it was occasionally found outdoors, but heavy frosts and scorching sun in recent years have caused its disappearance. With its dense foliage and gracefully weeping branches, it will grow relatively quickly in a favourable location to a height of 15 metres with equal spread. Glossy, dark-green, ovate leaves with pointed tips grow up to 10 cm long. The fruit is very small and red when ripe. In Arriyadh it is best in a warm-winter patio or garden in semi-shade. F. benjamina prefers deep, moist soils with good drainage and requires regular irrigation, more during the first years, and after establishment it will withstand short periods of drought. It needs wind protection when young. Propagation is by cuttings or air-layering. Occasionally cholorotic in Arriyadh’s soils, trees are prone to attacks by mealybugs. Expanding roots can be invasive and cause damage to underground pipes and paving; they also make it difficult for other plants to grow close by. As accent or focal point trees, they are also very attractive in containers. Trees can be clipped to shape and regular pruning will improve appearance, but pruning must be drastic if the branches are caught by a hard frost.

Chinese Laurel Fig

This Ficus is a curiosity in that it is usually grown commercially as a bonsai tree. It was first seen in containers in Arriyadh nurseries and has been planted outside shops and restaurant windows principally because it grows compactly and can easily be pruned to shape. Often available in a spherical shape on a stem, F. panda shares all of the requirements of F. m. var. nitida, and the same applies to its ability to withstand frost and sun. It has light, almost round, thick leaves, which alternate up the stem and a brown to reddish bark dotted with small horizontal flecks. It can be propagated easily from cuttings. It suffers from several diseases, including black fly, scale, thrips and eelworm, as well as fungus and rot. Probably a variety of Ficus microcarpa, it seems to have originated in nurseries catering for indoor plants and was then exported to nurseries in the Gulf States, where it has thrived in the coastal climate and made an excellent hedge plant. In the US, two new forms of F. microcarpa entered the Florida trade in the mid 1970s (CE) under the names Ficus ‘Green Island’ and Ficus microcarpa var. crassifolia ‘Green Mound’. Both have been sold as Ficus ‘Panda’ or Ficus americana ‘Panda’ in Europe. They tend to spread out and are easy to train as a ground-hugging shrub. For best results, F. panda is best planted in a sheltered position, in the humid environment of a well-irrigated garden. F. panda is also a good screening or background shrub that needs almost no pruning to stay dense and trim.

Umbrella Plant

The Umbrella Plant is a grass-like, subtropical perennial native to southern Africa and Madagascar. Now regularly seen in Arriyadh, it was previously observed or was planted close to water, but now seems to have ‘escaped’ and has seeded itself successfully in drier soils. It grows upright culms with flat, linear leaves radiated on top. The plants are evergreen and grow to 1 metre in height. Ideal habitats are moist with a high nutrient content. Spreading rhizomes form huge clumps that may capture riverbanks and pond-sides. In summer, plain, brown flowers occur on top of the whorls. Umbrella Plants are grown for their picturesque appearance. They give a lush, exotic impact next to any kind of water feature. They are one of the few plants adapted to waterlogged sites, but also tolerate locations with average moisture, where they are less invasive. Partial sun suits them best. Frost kills the plant’s foliage but it revives as soon as temperatures rise again in spring. They are readily propagated by seeds or may be divided at any time of the year. Maintenance is limited to the occasional removal of dead or unsightly leaves. If neglected in suitable environments, small, shallow ponds and swamps may be overgrown. Umbrella Plants are generally traded as Cyperus alternifolius or mistaken for their larger relatives, Papyrus. A dwarf type is Cyperus involucratus f. gracilis, with a height of some 30 cm suitable for containers and even pots to grow indoors. A cultivar called ‘Variegatus’ reaches about 1.2 metres and has white leaf margins.

Greek Myrtle

Myrtus is also called the Greek Myrtle; in Arabic, it is known as ass or hinbleiss. The Greek word ‘myron’ means balsam or odorous sap. It is a shrub of Mediterranean origin. The area of distribution reaches from the Canary Islands and the Mediterranean basin to southwest Asia. Often seen in Arriyadh as a hedge, the Myrtle reaches a height between 1 and 5 metres and a spread of between 3 and 4 metres. The shrub is often multi-branched and round in shape. The foliage is evergreen; the leaves are dark green, small and lanceolate. The blossom appears in summer and the beautiful white single flowers have attractive filaments. The flowers have an appealing scent and even the leaves have a good spicy flavour when they are rubbed. After flowering, the shrub develops, dark-blue berries. Maintenance with moderate pruning is advisable. The Myrtle is resistant to urban microclimates, and can be used as screen and shelter plant. It is suitable for pedestrian precincts, public open space and urban areas, and even for small managed roof gardens and as a topiary plant. The original distribution in the Mediterranean climate should again be considered, which means that the Myrtle loves sunny locations, but with sufficient air-humidity and irrigation. It is vulnerable in the case of desiccation and high salinity. The soil should be penetrable and rocky, but not limey. Myrtles can be used as specimen trees or dominant plants, as well as hedges. Myrtles will provide appealing compositions in rock or steppe garden themes.

Oleander, diflah

The Oleander shrub originated in the Balkans, Caucasus and Middle East with their Mediterranean climates. The Arabic name for Oleander is diflah. Oleander is an evergreen shrub growing between 2 and 3 metres high. The shape of the shrub is mostly round or oval, and multi-branched. The leaves lanceolate in shape. The flowers are grouped in an umbelliferous raceme, appearing in summer and quite enchanting. The variety ‘Album’ is distinguished by a brilliant white, ‘Pink Beauty’ in a fresh pink as the name implies, and ‘Sealy Pink’ flowers with a bright pink. After flowering, elongated star-shaped fruits appear. The root system is extensive. Maintenance of the Oleander is minimal and pruning can be done frequently to the base so it is able to rejuvenate from the ground up. All parts of Oleander are completely poisonous. Propagation can be done by sowing and pricking and by cuttings. The Oleander prefers a full sunny location and is moderately frost resistant. Irrigation should be moderate, because it likes moist soil. It can withstand a high salinity level. The shrub is heat-resistant and can withstand short-term desiccation. The shrub can be used as specimen, dominant plant, grouped or massed planting, and as a flowering hedge. Owing to the strong root system, it is suitable as a bank stabiliser and for environmental consolidation. In landscape design, it will produce good effects as shelter or screen plant. Park planting, public open spaces, urban areas and container planting are all possible with this attractive shrub.

Arrowhead Vine

Native to tropical South America, the Arrowhead Vine is a lush plant for a private garden in Arriyadh that has a suitable microclimate. A perennial, evergreen, climbing plant attaining about 1.5 metres, it is more often seen as a creeping groundcover than a climber in a tropical garden. The attractive, patterned leaves are alternate, simple, arrow-shaped and often mottled; deep-olive-green leaves have prominent white veins. Numerous cultivars have been developed that vary in size, shape and colour, and the foliage of some of them is somewhat cream-coloured with green edges. Young leaves, divided into three, deep-cut lobes, are rounded at the tips and up to 15 cm long. When older, they can be up to 25 cm long and are divided into more segments. The flowers bloom on an elongated whitish spike. Syngonium requires moist, fertile, garden soil and a minimum winter temperature of 16°C. The plants also require high humidity, meaning that misting the leaves regularly, as well as protection from cold weather, is necessary in Arriyadh. They need strong but not direct sunlight, and abundant water from spring to autumn, with less in winter. Fertilising improves growth in spring and summer. Propagation is by cuttings or air layering. Syngonium species are often grown as house plants; they are also good container plants on patios. Climbing stems can be pruned away and the plant will become bushier and the leaves more attractive. The Arrowhead Vine is a high-maintenance plant requiring special attention for it to be grown in Arriyadh.

Lemon-Scented Geranium

In South Africa’s Cape Province, it is possible to find Lemon Geraniums growing wild in scrub vegetation or light woodland. It is considered a sub-shrub for its herbaceous branches sprouting from a woody base to some 90 cm in height. Nevertheless, these upright bushes are also grown as annual plants in pots or beddings for combining attractive pink flowers with a pleasant fragrance. The crinkled foliage grows very dense so that plants are easily formed in any shape desired. The specific name refers to the texture of its foliage, since crispum means curly. When touched, the glandular, evergreen leaves release a strong lemon scent. They are cordate in shape and fresh green. In Arriyadh’s climate, where it makes a good garden plant, it should be protected from full sun and drying winds. Short dry periods are tolerated, but this species does better with frequent watering in well-drained soil. To guarantee appropriate moisture and allow aeration at the same time, the ground is best improved by adding compost and perlite. All-purpose fertiliser can be applied frequently. Lemon Geraniums do not take frost, extreme heat is best endured in semi-shade locations. Plants stressed by adverse growing conditions are sometimes infested by spider mites or mildew. Propagation by seed is started in late winter, while softwood cuttings may be planted in late summer. The main flowering period is spring to early summer. Some varieties have been selected with more showy flowers and another cultivar, ‘Variegatum’, features leaves with ivory margins.

Croton

Better known as Croton, this evergreen shrub is widespread as a highly ornamental bush for the garden or as a popular indoor plant. It originates from India, Sri Lanka, Malaysia and Indonesia, where heat is accompanied by high atmospheric humidity and rainfall; hence, it demands abundant water. In Arriyadh, it withstands the sun and dry air relatively well, but requires a position sheltered from desiccating winds. The soil must be rich in humus and well drained. Crotons grow their colourful foliage in partial sun. High contents of nutrients and high temperatures may reduce the number of bright spots. Full sun bleaches the colours, while a lack of light results in greener leaves with less yellow or red spots. The intensely mottled foliage is shiny and attracts the eye from far, the major asset of Crotons. Plenty of varieties are bred such as ‘Petra’, with yellow veins and red shades alternating with green. Its white flowers are insignificant. Favourable conditions let it grow into a V-shaped bush of about 2.5 metres high and up to 2 metres wide. High levels of humus are important, and it should not be exposed to drying winds. Severe cutting back is possible in early spring, if frost has damaged the leaves. It does well in containers, is an ideal indoor plant and makes excellent focal points or colourful hedges. Stressed plants may occasionally be infected by mealybugs or scale. Both cuttings and layering make for strong offspring easily. In public gardens, it may as well be too exotic, but should be restricted to special sites.

Painted Nettle

The Painted Nettle is one of the most popular plants for interior greening, and is widely used outdoors where its conditions are met. They are tender perennials from southeast Asia found in shady, humid environments. If grown as bedding plants, they create masses of multi-coloured foliage to a height of about 30 cm. They are more valued when planted in mixed borders, where they grow twice as high to form a round, bushy eye-catcher. The variegation is outstanding, in shades of green, yellow, scarlet, red, pink and ivory. Terminal flower spikes feature azure florets that are usually pinched out, since the foliage is this plant’s main, spectacular attraction. In Arriyadh’s winters, Painted Nettles take full sun, but during the summer they are best sheltered, especially during the afternoons. Frost instantly kills this plant, and strong winds twist the leaves or entire branches. It appreciates fertile soil with ample water, but without waterlogging. It is very easy to grow in pots and containers. The easiest method of propagation is by placing cuttings in water or planting them in a mixture of peat, compost and sand with some cover to reduce transpiration. Sowing is an alternative in order to pick one of many colourful varieties, or to achieve random forms. They respond well to fertilising and do best with occasional pruning to rejuvenate the stems. Frequent pinching is recommended to form a denser habit. Their moderate to high maintenance requirements limit the use of Painted Nettles to well-kept gardens and pedestrian precincts.

Loquat

Eriobotrya, commonly known as Loquat, is an evergreen shrub or small tree with a compact, rounded structure that reaches a height of between 3 and 8 metres. It is indigenous to Central China and South Japan, and seen in Arriyadh only in sheltered gardens and farms. The bark and young branches are woolly and the large, deep-veined and saw-toothed leaves are glossy, dark green on top and rusty underneath; they are elliptically shaped and up to 30 cm long. Clusters of small, white, rose-like flowers appear at the branch endings in panicles in autumn and winter, exuding a scent of vanilla. The small, edible, round fruit is deep-yellow in colour, and sweet in flavour. The large seed can be squeezed out of the fleshy fruit. Loquat is deep rooting and likes well-drained, but moist soil, and is nevertheless quite drought-tolerant. Growth rate and salt tolerance are moderate. E. japonica can be propagated by seed or cuttings. It is an appealing, small tree for a protected, private garden or patio or a large container, because of its attractive foliage, flowers and fruit. Best planted in wind-sheltered locations, Loquat will make an excellent specimen, dominant or edging plant in a park, too, if sheltered. It requires a rich dressing of fertiliser in spring, and is susceptible to fireblight, root fungus and mealybugs. Maintenance is moderate and pruning is required from time to time to improve the tree’s shape and to thin out the interior branches, to allow sunlight to reach inside. In this way, fruit-bearing will be increased.

Bottle Tree, boudret al afreet

This Brachychiton is more drought-resistant than B. acerifolius. It tolerates full sun and a hot desert climate, just like in its native country, the semi-arid inland of eastern Australia. Trees are found growing there amongst rocks of granite or limestone, but also thriving in deep soil. Narrow and pyramidal when young, the plant’s name refers to the widened base of the trunk which is an adaptation for storing water during prolonged periods without rainfall. On the other hand, it responds well to irrigation by growing faster. It may reach 10 metres easily, while 20 metres are to be expected only in its native environment. Known in Arabic as boudret al afreet, it is often seen in Arriyadh, where the shiny, bright-green fluttering leaves provide a lush effect. The green bark is smooth and attractive. They allow distinguishing two subspecies; Brachychiton populneus ssp. populneus has reduced lateral lobes, while three or five lobes create the palmate leaf of ssp. trilobus. Both subspecies have flowers in light yellow with purple centre appearing in spring. Cultivars may also flower in pink or red. Stagnant water is one factor to avoid definitely, hence soil should drain well. This tree blends in well in desert landscapes, creating dense shade. Not many trees do as well in lawn areas as the Bottle Tree. The root zone should be soaked thoroughly every couple of months in summer. It survives in an urban microclimate, but the littering fruit and annoying itchy hairs limit it to area where the dry pods do not affect passers-by.

Creeping Fig

A very common creeper in tropical countries originating in Asia, the Creeping Fig is a vigorous, self-clinging, evergreen vine that attaches itself to surfaces via aerial rootlets. Its small leaves are heart-shaped in their juvenile state, forming an interesting pattern on a wall, while the plant is still young; later, the leaves become much larger, up to 10 cm long, oblong and leathery, when mature. The vine will then cover large areas of the wall completely and quickly. A mature plant will reach 5 metres and more and develop woody branches which stand out up to 60 cm from a wall. Flowers are insignificant and rare, as are the fig-like but inedible fruits which occasionally appear on plants throughout the year. F. pumila will climb on most surfaces and is good on trellises, in shady locations especially on north- or east-facing walls, where it grows best in Arriyadh. Morning sun is tolerated. Propagation is by seed, cuttings or offsets. Best in fertile garden soil, it is sometimes subject to root knot nematodes and root rot. Frost damage is caused at –10°C, but the vine will survive with warmth radiated from a supporting wall. It requires moderate, but regular irrigation. Maintenance is low, but the plant can become a nuisance if it gets out of control and it can be difficult to remove from a wall – top-heavy plants, on the other hand, may peel away. It can be cut to the ground to encourage new juvenile growth or to prevent it becoming too invasive. The variety ‘Minima’ retains the small leaf form for a longer period.

Common White Jasmine, Poet’s Jasmine

The Poet’s Jasmine originates from southwest Asia. It received its name from the Persian word for ‘gift from God’. In Arriyadh, it is slow to grow at first and rather frost-tender. Although it needs support like wires or a fence, it may reach a height of up to 8 metres. The glossy, evergreen foliage consists of five or seven oval leaflets and is arranged opposite along glabrous, green twigs. They last in winter and withstand low temperatures better than those of other species. White, slender buds open to produce funnel-shaped white flowers in summer. Their scent is marvellous and attracts attention immediately. Inflorescences have five corolla lobes. The soil should be nutrient-rich and well-drained. Poet’s Jasmine grows well in containers. It should be watered freely in spring and summer, but sparsely in winter. They are heavy feeders and do best with general-purpose fertilisers. Jasmines are of cultural importance as the symbolic flower of Damascus or as the national flower in Pakistan and the Philippines. Jasminum officinale ‘Flore Pleno’ grows double flowers, and there are varieties with yellow or variegated leaves which should not be exposed to full sun. They are easily propagated by cuttings in September. Another simple method is layering stems for one growing season and to separate them from the mother plant, well rooted and ready to flower within one year. Previously considered a cultivar, a large-flowered jasmine is now classified as an independent species: Jasminum grandiflorum.

Mother-in-Law’s Tongue, Snake Plant

This species is traded as Bowstring Hemp, Mother-in-Law's Tongue or Snake Plant. It originates from Nigerian woodlands and has since long been cultivated as a long-living indoor plant and as reliable outdoor perennial resisting harsh conditions. Dagger-shaped, evergreen leaves form dense clumps emerging from fleshy roots and rhizomes that spread the plant slowly. Their dark-green is mottled with very light-green horizontal lines. They may be propagated by leaf cuttings while cultivars need to be multiplied by dividing clumps. Very common is ‘Laurentii’ with yellow lines along the margin. It should not be exposed to full sunlight where the edges easily get burned. Leaf cuttings from this cultivar degenerate to offsprings with green leaves without variegation. Another popular variety is ‘Hahnii’ growing compact to about 30 cm height. The species and ‘Laurentii’ both grow to about 1.5 metre high. Plenty of light is required to induce the development of flowering stalks. They bear greenish inflorescences that release pleasant scent. Established plants take drought for weeks, but turn pale if totally neglected. The soil should be moderately fertile and drain well since over watering kills the plants quickly. Snake Plants can be used outside as accent plants in rock gardens. Being free of pests and diseases and demanding no maintenance this species and its cultivars should be used more often in Riyadh’s public and private gardens, where the will need some shelter. They earn the vernacular name Bowstring Hemp for their strong leaf fibres.

Rose Geranium

Rose Geranium is grown for its intensely scented leaves. It is an erect, branched bush growing to 1 metre high with equivalent width, originating from the Cape Province, South Africa. Its hairy, fleshy stems become woody and brittle with age and are densely covered with evergreen, wrinkled foliage in fresh green. Coated in glandular hair, they instantly release a strong odour of roses, hence its common name. Its fragrance is also the reason for the species’ name since, in Latin, graveolens means strong-smelling. They are used to manufacture geranium oil which is far less expensive than true rose oil. The pink or white flowers are smaller and less showy than the floral display of its relative Garden Geranium. Nevertheless, they look attractive and enhance a mixed border from late winter to summer, with a peak in spring. Rose Geraniums are used to hot summers and mild winters without frost. They do best in semi-shade positions protected from full sun in the early afternoon, and are an attractive addition to a garden in Arriyadh. The soil should be moist all year round, but brief periods of drought are tolerated. The plants are best grouped close to walkways to facilitate occasional brushing by pedestrians. They grow well in pots and containers if drainage is adequate. Soils may range from acidic to alkaline, but should not be compacted. Poor soils should be improved by compost, and some slow-release fertiliser every so often is welcome. Set amongst taller shrubs, this healthy plant makes an ideal filler.

Elephant's Food, Porkbush

This popular succulent is native to scrub vegetation, thickets and dry riverbeds in eastern South Africa and Mozambique. The Porkbush is now planted around the world for its ability to survive certain extremes. It stands heat and drought even as a pot plant, and may be used as a bonsai. It is often seen on footpaths and in planters in Arriyadh. The Porkbush usually grows as an oval or round shrub some 2 metres high, but under favourable conditions it can reach double this size. Reddish-brown, fleshy stems are aligned with round, succulent foliage. In early spring, tiny flowers emerge in light pink. Porkbushes take severe pruning. In its homeland, they are occasionally browsed by elephants and quickly recover from the base. Clipping and pinching allow the plant to be grown in any sculptural shape desired, or as a hedge. It can be grouped or grown as a specimen plant in rock gardens and any arid landscape. Some cultivars have peculiar characteristics, such as ‘Aurea’ with its yellow-green foliage and ‘Foliis variegatis’ with ivory leaf edges. Interesting is ‘Limpopo’ with larger, ovate leaves up to 3 cm in length and 2 cm in width. The foliage is edible and somewhat sour in taste. It brings relief to sore throats and cure mouth infections, as well as insect stings and sunburns. Its deep roots and resistance to drought make this shrub an ideal soil stabiliser on slopes. Both full sun and semi-shade are accepted. Propagation is very simple by cuttings that should be allowed to dry before being placed in a mix of sand and compost.

Grevillea, Silk Oak

The Silk Oak is a strong, enduring tree that reaches a maximum height of 50 metres. However, such growth can be expected only in its native country, Australia. Although it grows quite fast, it will usually not exceed 13 metres, especially in Arriyadh. The tree has a conical, upright form. Fern-like, lacy leaves are shiny green on top and silvery below, while the showy orange flowers are borne in large clusters on the branches, usually when the tree is in a semi-deciduous state after the winter. Silk Oaks are considered evergreen, but foliage may be shed owing to cold, or when the new leaves appear. It will tolerate a wide variety of soils, but these should be well drained. Waterlogging and alkaline desert soils limit the speed of growth and cause iron chlorosis. The wood is brittle and wind exposure may cause branches to die back or break off. Propagation is by seed or cuttings. G. robusta is a background tree for use in parks and in public squares. A mature tree makes a picturesque silhouette against the sky. Heavy pruning is possible, but may spoil the columnar or pyramidal shape. It has toxic qualities. Grevilleas may sometimes cause painful skin irritation. Regular irrigation is necessary at first, but a mature tree is generally drought-resistant and requires a deep soaking every month or so. Heavy leaf litter in spring necessitates a lot of tidying up from lawns and paving, although it can be left as mulch on the soil. This tree is rarely seen in Arriyadh, although it has potential for planting in protected situations.

Jacaranda, Mimosa-Leaved Ebony

Native to tropical South America, this deciduous tree is an eye-catcher in full flower with large panicles of lilac or pale blue. These appear in spring before the foliage fully forms. Flowers may appear again in autumn, but less obviously, because of the dense bipinnate leaves. They resemble those of some acacias – hence its species’ name mimosifolia – but may immediately be distinguished for their opposite phyllotaxy. Jacaranda comes from the vernacular Brazilian name. They grow fast to a height of about 10 metres and equivalent width in sunny positions when the soil is fertile and frequently watered. The soil should contain compost and be fast-draining. Unfavourable conditions such as compacted soil or continual drought will lead to dead branches. The shallow-growing roots must not be damaged. Jacaranda is not often seen in Arriyadh; it is not particularly well suited to the climate and its growth often comes to a standstill. In Arriyadh’s coldest regions, the Jacaranda’s twigs may freeze, but trees soon recover just as if they had been pruned. The tree can be cut back in late winter. Large, flat, red-brown fruits somehow resemble ravioli and reveal seeds that easily germinate if watered for 24 hours before sowing. Jacarandas may be grown in pots for their attractive fern-like leaves, but flowers will not appear on such plants. Mature trees are flat-topped and their lacy foliage creates light summer shade. With summer humidity, they make specimens for pedestrian areas. In Arriyadh, unfortunately, they are not very successful.

Peregrina

Native to Cuba, this tall, dense, rounded evergreen shrub, commonly known as Peregrina, grows up to 3 metres high with an equal spread, and when mature will be almost like a tree with several slender trunks. It has been quite successful in Arriyadh in recent years, in both parks and gardens, as well as in urban situations. The glossy, oval leaves are about 10 cm long, medium-green and velvety on the upper surface. Bright scarlet, five-petalled, star-shaped flowers with yellow stamens bloom in clusters in summer. J. integerrima does best in full sun in frost-free locations, but will tolerate partial shade. In very cold winters in Arriyadh, it may become semi-deciduous, but the main stems are hardy. It requires regular irrigation, especially in late spring and summer, but can be classed as a drought-tolerant plant, once established. Tolerant of a wide variety of poor and dry soils, as long as these are well draining, the shrub is not tolerant of salinity. It flowers on the current year’s growth, so it can be pruned at any time of the year. All parts of the plant contain toxic substances. Propagation is from cuttings taken in spring. A slow-release fertiliser, applied two to four times a year, will improve the plant’s appearance. J. integerrima is a spectacular shrub in flower and can be used as an accent or in a shrub border. It is also a fine container plant for patios. Suitable for planting in buffer strips such as road medians and in urban landscapes squares, some protection is necessary against hot desiccating winds.

Flaming Katy

While most succulents are grown for their remarkable foliage, thickened stems or spectacular thorns, this succulent attracts attention with its brightly coloured flowers. Native to Madagascar, Flaming Katies grow a compact, round shape to about 40 cm high. Their fleshy, deep-green leaves are round or oval with scalloped edges. Clusters of small tubular flowers show up in the colours white, yellow, orange, red, pink or purple. They appear in winter for weeks. The Flaming Katy may grow as a tough indoor plant or as a highly ornamental bedding plant. The soil should be well drained. The most frequent problems for pot-grown Kalanchoes are overwatering and applying cold water that shocks the roots. During dry periods with insufficient watering, the leaves begin to turn yellow and shrivel up before they are dropped. This starts from the bottom progressing upwards, until the branches bear remnants of foliage that will not become attractive again. Cutting back may result in rejuvenating growth, but it is more appropriate to replace the entire planting. After flowering, the flower stalks should be cut off to give a neat appearance and to induce the production of new buds. A disadvantage is the brittle leaves and branches. They are easily damaged, which means that the Flaming Katy should be located carefully. In Arriyadh’s climate, it does best if not exposed to full sun, especially in the afternoon. It should be used to bring its splendid colours into shady areas. It is very easy to multiply Flaming Katy by cuttings in spring or autumn.

Devil’s Backbone, Maternity Plant

The Devil’s Backbone originates from southwest Madagascar, where the climate is quite similar to the dry, hot and rocky conditions in Arriyadh. It makes a gnarled round bush of about 1 metres in height. This succulent grows green stems sparsely aligned with opposite, fleshy leaves that produce tiny plantlets along the edges. These pseudo-bulbils appear in summer and root even before touching the ground. This may result in an abundant number of new plants and so this Kalanchoe has earned the other common name Maternity Plant. The foliage is pale-green freckled in red, and may bend upwards in dry conditions. Older plants show clusters of bright orange, tubular flowers at the beginning of summer. In autumn, the floral stems should be cut back and vigorous growth is achieved after pruning the plant back to the ground. The soil must be sandy to ensure excellent drainage. Established plants tolerate full sun and heat, but should be watered frequently. Partially sunny locations are also eligible, especially with some shade in the afternoon. While the Devil’s Backbone is resilient to most desert conditions, it will be killed by frost and overwatering. It makes an ideal specimen in rock gardens and can be grown in pots as a house plant or in containers to embellish a terrace or courtyard. They should be pinched occasionally to obtain lateral branching and a more compact growth. Maintenance requirements are low in appropriate locations. A serious hazard is the plant’s toxicity if ingested by livestock.

Olive, zaytoun

Olea europea is known in English as the Olive tree, and in Arabic zaytoun. Its distribution extends from the Mediterranean to southeast Africa and southwest Asia. The tree can grow to between 6 and 9 metres high with a spread of 6 to 8 metres. Often, the Olive tree features a very picturesque growth with a dense crown. The leaves are entire and lanceolate, with the typical olive green on the top and silvery-green underneath. The flowers are unimpressive, but the fruits are famous and popular in all regions where olive trees grow. Maintenance is minimal; regular pruning will densify the crown. Olives do not like stagnant water, but otherwise have no special soil requirements. Frost-tolerant to –10°C, the trees are prone to attack by scale insects and crown gall; verticillium wilt and black scale can also become problems. It is a shelter plant, and can be used in open public spaces, park planting and urban areas. Olives can also be grown in small managed roof gardens or containers. For landscape design, however, it should be recognised that the Olive is a fruit tree, i.e. its use is inadvisable next to pedestrian areas. Olives make appealing trees as specimens, grouped planting or linear planting. They will lend a natural Mediterranean garden flair to steppe gardens. Propagation is by cuttings and grafting. To ensure optimal development of the tree, it is necessary to provide a minimum of air humidity. Olive tree plantations have been successful in Arriyadh, and can now be seen quite often.

Bougainvillea, Paper Flower, janamiyah

Bougainvillea, or janamiyah in Arabic, is a woody climber with an armour of strong thorns. It provides vivid splashes of colour in an arid environment and grows well in Arriyadh, although it will tolerate only a few degrees below freezing. On appropriate supports, it may reach a height of 10 metres with relatively fast growth rate. It tolerates full sun, wind if trained well on its support. The plant’s vigorous nature necessitates frequent attention and the branches require strong trellises or pergolas. In favourable conditions, the foliage is evergreen, while the tiny flower itself is white and insignificant. Much more spectacular are the clusters of papery bracts that come in shades of violet, magenta, pink, red, orange and white. Good drainage, nutrient-rich soil and frequent irrigation allow it to grow rapidly and produce a multitude of flowers from spring till autumn. During the winter months, the plants survive with little and should not be fertilised, in order to allow the plants to rest. Urban microclimates and drought are also tolerated, but at the cost of appearance. Bougainvillea glabra ‘Mini Thai’ is a dwarf variety with purple bracts. It grows slowly to a hemispherical, compact shrub 1.5 metres high and about 2 metres wide. This plant is best suited to growing in containers. Propagation is easy by means of hardwood cuttings in spring. Offshoots should be covered during rooting to ensure high humidity. Winter pruning of frost-damaged wood should be avoided, because it shelters new growth from surviving wood.

Bougainvillea, Paper Flower, janamiyah

The generic name for Showy Bougainvillea was given in honour of Admiral Comte de Bougainville, who sponsored a journey to Brazil where the plant originates. It is probably the better choice for Arriyadh, because it is hardier than B. glabra. This sprawling climber is well protected by strong, curved thorns on hairy, woody stems. Its leaves are smaller than B. glabra and shiny on top and soft and hairy underneath. They last during mild winters, but are sometimes shed if conditions are unfavourable. The specific epithet stands for the spectacular colourful clusters of white, pink, red or purple flowers that appear seasonally, especially in spring. Three true, pale-yellow flowers are surrounded by bracts that make the magnificent display. Dormancy factors such as low temperatures or drought seem to trigger flowering. Its vigorous growth up to 20 metres, depending on its support, demands frequent pruning, and branches need to be attached to a wall, pergola, trellis or strong fence. Showy Bougainvilleas may also be hedged. Clipping is possible at any time of the year, but severe cutting should be done after the flowering season in autumn. This species may even be grown as a bonsai or topiary plant. Full sun and nutrient-rich, well-drained garden soil suit it best. In pots or containers, plants should be given a soluble fertiliser weekly, except in winter. On north-facing walls, the lack of light results in few or no flowers. The numerous cultivars are easily propagated by hardwood cuttings placed in indirect sunlight.

Australian Flame Tree, Flame Kurrajong

Australian Flame Trees have maple-like, semi-evergreen foliage. Showy red flowers appear in spring when branches are still bare. Like flames the blossom attracts the eye immediately. They are small but plenty, bell-shaped and grouped on branched, red stalks. They are worth waiting for, since trees do not bloom so spectacularly until they are 20 years old or more. Both flowering and durability of its leaves can vary from year to year, presumably depending on climatic conditions. The Australian Flame Tree is native to Queensland and New South Wales where it grows to a height of about 36 metres. In Riyadh it usually does not exceed 15 metres with about 10 metres across, where it requires shelter against hot, desiccating, strong winds. The straight trunk is covered in green bark that turns light grey with age. Young leaves emerge in pink and turn green as they mature. They are deeper lobed than those of maple trees. In late summer boat-shaped fruits ripen and release edible, yellow seeds. Australian Flame Trees thrive in full sun and deep, fertile soil which should be low in salt. The root zone should be soaked thoroughly every month during the summer. Drainage is important and some humus should be added, if the ground is alkaline. Phosphorus is important and irrigation should be stopped in winter to induce flowering. Due to its uniform appearance it makes an ideal street tree. Popular in parks, it creates pleasant shade for pedestrians. Young plants should be protected from frost. Established trees simply shed their foliage in cold weather without any further damage. A central leader should be encouraged by removing lower branches. Fallen spent blooms and seed pods may cause a litter problem.

Snow Bush

This is a medium-sized, showy, tropical shrub actually originating in the South Pacific, but now gradually being seen in Arriyadh in intensively designed open spaces that are regularly irrigated and thus have the level of moisture that this plant requires. Its basic attraction is the variegated leaves, which at a distance look like flowers, and the white mottled leaves look as if they have been snowed on. B. disticha var. ‘Roseo-picta’ has a mixture of green, white, pink and red leaves on pink and red stems in a zigzagged fashion. The small, greenish, petal-less flowers are inconspicuous. The shrub thrives in partial or light dappled shade. Not frost-hardy, foliage will return after the winter. It is propagated by softwood cuttings in summer or root suckers. Pinching out stem tips when young will promote branching growth. The plants, which spread with their root suckers, can be invasive in a garden. It also drops its seeds frequently, which then germinate quickly underneath the plant. Good for mass planting, as a useful background shrub, or as an accent in a shrub border, it can also be clipped as a hedge or used as an edging plant. The dwarf variegated form is useful as a ground cover and the pink leaves are attractive in containers. B. disticha requires high maintenance, and, needs regular fertilising with nitrogen and potassium. Regular trimming promotes compact, new growth, and thus a new display of colour. Shrubs require regular irrigation and consistently moist soil, since otherwise leaf drop may occur.