Wild plants are a vital component in all terrestrial ecosystems. All living things on earth are totally or partially dependent on plants and plant products in one way or the other. Kingdom of Saudi Arabia has a varied heritage of biodiversity, encompassing a wide spectrum of habitats ranging from mountains, sand seas, rocky deserts, meadows, salt pans, etc. and a variety of climatic regimes, ranging from Mediterranean, semiarid and arid climates.                  

                     Vegetation of the Central and Eastern regions is generally sparse. Annual plants, which constitute about 60% of the vegetation cover, are dominating in wadis and other shallow depressions such as Ammariyah,

 Huraymala, Raudhat Khuraim, etc. Most of these ephemerals start their life cycle during winter and shed seeds within 2-3-months. Perennial species, on the other hand, produce new shoots during rainy season and appear to be remain dormant during summer. Some of the dominating perennial species are Acacia spp., Rhazya stricta, Pulicaria undulata, Rhanterium epapposum, Haloxylong salicornicum, Lycium shawii, Calotropis procera, Ziziphus nummularia, etc. Vegetation of sandy deserts are also very sparse.

The common shrubs and shrublets of the sand-dunes of Dahna and Nafud Deserts are Artemisia monosperma, Haloxylon persicum, H. salicornicum, Calligonum comosum. All these shrubs usually seen along with perennial herbs and grasses like Scrophularia hypercifolia, S. deserti Moltkiopsis ciliata, Cyperus conglomeratus, Stipagrostis drarii ,Centropodia fragilis, etc.      

 Vegetation of the northern part of the country is also dominated by annual  species. However, perennial components such as salsola spp., Traganum nudatum, Haloxylon salicornicum, Haloxylon persicum, Artemisia spp., Zilla spinosa, etc. are forming large communities in all range lands. In general, the entire area is divided into Nafud, Hammad, Harrah, Widyan, El-Shama and Wadi Sirhan, each of which has a characteristic vegetation.

 The mountains on the western and northwestern regions are discontinuous. Vegetation on high altitude areas of these mountains is dominated by Juniperus phoenicea, Olea europaea, Acacia etbaica, Commiphora spp., Prunus korschiniskii, Launaea acanthodes, etc. Wadis and foothills are sparsely vegetated. Scattered populations of Acacia tortilis, Maerua crassifolia, Ficus palmata, Moringa peregrina, Ocharadenus baccatus, etc. can be seen in these areas.

Vegetation of southwestern mountains, particularly in Asir and surrounding areas, is dense and consists of species with North East African affinity. Juniperus procera, Olea europaea, Acacia asak, Acacia seyal, Teclea nobilis, Nuxia oppositifolia, Nuxia spp. along with Euryops arabicus, Lavandula dentata, Rumex nervosus, Dodonaea angustifolia, Cluytia myricoides, etc are the dominant plants of high altitude areas. Slopes of the mountains also posses a dense vegetation, mostly dominated by Acacia asak, Maesa lanceolata, Carrisa edulis, Delonix elata, Acacia hamulosa, Cadia purpurea, etc. The ravines and gullies at lower levels also posses a relatively dense vegetation, mostly dominated by Ficus palmata ssp. salicifolia, Acacia etbaica, Cadia purpurea, Ziziphus spina-christi  and a  number succulents such as Caralluma, Sansevieria, Ceropegia, etc.

           However, the eastern slopes of the entire southern Hijaz are rain-shadow regions. Vegetation on the eastern side of the escarpments is mostly dominated by succulents like Euphorbia and Aloe. Vegetation on the extreme southwest mountains is more or less similar to that of Yemen. In Jabal Fayfa, the dominant species of the high altitude areas are Juniperus procera, Acacia mellifera, Ficus sycomorus, Euclea schimperi, Dracaena ombet, Acacia seyal, etc. while in low altitudes, the species composition is dominated by Commiphora spp., Trichellia emetica, Delonix elata, Mimusops laurifolia, etc.

 Low lying areas and other open plains in the Tihama region are with scattered populations. However, in certain areas dense populations of Acacia tortilis, Leptadenia pyrotechnica, Suaeda monoica, Hyphaene thebaica, Salvadora persica, Panicum turgidum, Tamarix nilotica, etc can be seen.

Succulent species and halophytes are dominating  in and around salt pans (Sabkhahs). Species such as Zygophyllum coccineum, Aeluropus lagopoides, Cressa cretica, Limonium axillare, Zygophyllum simplex are common in these areas while Avicennia marina and large colonies of sea grasses are dominating in sea shores.

Saudi Arabia does not have any rivers or even any perennial stream. However, seasonal streams or ponds, mostly seen in the southwestern region contain a few species. The aquatic flora in Saudi Arabia contains more than 40 species (aquatic and semi aquatic), of which Potamogetonaceae has the maximum number of species.   

Last updated on 20-5-2007  site conceived and maintained by dr. jacob thomas, dept. of botany and microbiology, king saud university, riyadh.

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