Northern Tihama

Plant diversity in Saudi Arabia Northern Tihama
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Northern Tihama is a narrow strip of undulated coastal zone situated between Red Sea on its western side and a chain of mountains (Hijaz) on its entire eastern side. It is a 1080 km long sandy and silt area extending from Jeddah in the south to Haql town in the north. The strip is more or less at sea level in the south or slightly elevated towards east as a result of the silt coming from the Hijaz Mountains. The plains along the eastern side of the coastal zone is wide in the southern parts (between Jeddah and Yanbu) and narrow in the northern sector, north of Yanbu. Tihama is virtually absent near Haql area where its sea shore merges with the foothills of escarpments. Shore line is somewhat undulate margined with some creeks penetrating into the land. Rainfall is erratic along the coast, occurring mainly between October and February. Less than 20 mm rainfall is recorded in the Jeddah and Yanbu stations. Maximum average temperature ranges between 25 and 33 ⁰C and humidity ranges between 50-75%. Unlike the southern Tihama region, the mangrove population is not dense and continuous in the entire coastal marshy land except in some of the creeks near Thuwal, Yanbu and in some islands off Al-Wajh where dense stands of healthy Avicennia marina could be seen. The northern limit of the distribution of Avicennia marina along the Red Coast in Saudi Arbia appears to be near Sharm Zubeir, off the coast between Al-Sourah and Sharmaa. Rhizophora mucronata, the only other mangrove reported along Red Sea coast is also found in a few locations north of Jeddah (Umm Ruma Island, Dugm Sabq, Gama'an Island, Shibara Island, etc). However, its main populations are found in Al Wajh Bank, an Archipelago comprised of about 50 islands located south west of Al Wajh. Unlike the southern Red Sea Islands, northern Red Sea Islands (Al Wajh Bank) are devoid of any dense vegetation. Majority of these islands are sandy while others are rocky with small hillocks of 5m high or less. Vegetation is almost nil in most of the islands except in a few where salt bushes such as Arthrocnemum macrostachyum, Halocnemum strobilaceum, Zygophyllum spp. etc dominate in patches.
Arthrocnemum macrostachyum (forefront). Avicennia marina (distant)			The plains of Northern Tihama are composed of stones and sand with differing soil depths. Vegetation between Jeddah and Yanbu is more or less similar to the that of the plains of southern Tihama. The most dominant among them is the widely spaced Acacia tortilis-Maerua crassifolia association. However, M. crassifolia is in a highly degraded state, mostly seen as heavily grazed and cushion-formed. Other Capparaceae species dominant in the sand dunes and stony plains of southern Tihama, such as Dipterygium glaucum, Cadaba glandulosa are less frequent north of Jeddah. Similarly Commiphora spp., dominant in the foothills of southern Tihama, is almost nil in the northern Tihama. Most of the areas during summer are dry and barren. Dominant species of the plains and foot hills are the scattered A. tortilis intermixed with A. ehrenbergiana. Abutilon pannosum, Lycium shawii, Ochradenus baccatus, etc. dominate in shallow silt depressions and Leptadenia pyrtotechnica and Rhazya stricta dominate in sandy hummocks. Common grasses in these areas are Panicum turgidum, Pennisetum divisum and occasionally Lasiurus scindicus and Aristida spp. Coastal areas are mainly dominated by salt bushes composed of chenopods and Zygophyllum spp. Limonium axillare, Arthrocnemum macrostachyum, Halopeplis perfoliata and Zygophyllum coccineum are the most dominant along the northern sabkhas. In general, L. axillare grow in low lying areas or in localized depressions while Z. coccineum dominate in areas covered by coral rocks or coral sands. The areas north of Jeddah the coastal zone is covered by white coral sand supporting dense stands of Suaeda monoica and Anabasis setifera. On the eastern side where the soil is less saline, the vegetation is dominated by Acacia ehrenbergiana, Anastatica heirochuntica, Senna italica and Hyparrhenia hirta. Sabkhas of the coastal areas of Thuwal are densely vegetated with salt bushes. It supports Zygophyllum coccineum and Aeluropus lagopoides along with Desmostachya bipinnata, Indigofera oblongifolia and Astragalus spinosa in some locations. Sands overlain the crusty salt substratum support a number of annuals such as Sonchus oleraceus, Launaea mucronata,
Trees are generally few in the entire Tihama area. Among the large trees, Acacia raddiana, A. johnwoodii, Capparis decidua, Maerua crassifolia and Hyphaene thebaica, are prominent. Further north, the coastal zones near Rabigh and south of Yanbu are devoid of any appreciable level of vegetation due to the development of industries and corniches or occasionally with secondary vegetation dominated by Aeluropus lagopoides, Cressa cretica, Halopeplis perfoliata and Zygophyllum coccineum. At places where they form into dense stands sand accumulates at the base of these shrublets and provide habitats for other mesophytes such as Fagonia indica, Glinus lotoides, Lotus corniculatus, Picris cyanocarpa, etc. Ruderals and the common invasive species, Prosopis juliflora also dominate around new settlements and along road sides. Coastal lines of Yanbu are with several creeks, most of which provide shelters for the growth of Avicennia marina. Sea in this area is very shallow. Cymodocea rotundata, the wide leaved sea grass occurs in such waters. The coastal zone is bounded on the east by salty flats or small dunes of coral sand. In some places north of Yanbu industrial city, coastal areas are often enclosed by coral rock and drained sand gullies. Saline coasts are dominated by Arthrocnemum macrostachyum, Tamarix aucheriana, Suaeda vermiculata, Sporobolus spicatus, while the sandy soil towards the interiors are dominated by Acacia ehrenbergiana and A. tortilis associated with Taverniaria spartea. During spring, most of the herbaceous flora of the plains and foothills near Wajh and Umlaj are mostly seen along the drainage channels, alluvial plains and other silt filled depressions. Ravines are dominated by Gymnocarpos decander, Ochradenus baccatus, Zilla spinosa and Aerva javanica. Another striking species in the area is the Retama raetam, usually found in plains close to foothills.
Coastal areas of Duba is dominated by Aeluropus lagopoides, Juncus rigidus and Nitraria retusa. In some places it is seen in close associations with Haloxylon salicornicum, Seidletzia rosmarinus, Suaeda monoica or Zygophyllum coccineum. Open plains, not far away from the coastal zone, the branched palm tree, Hyphaene thebaica is seen intermixed with Acacia ehrenbergiana. The extreme northern side near Haql, Tihama is narrow with a rocky terrain. In some places the escarpment is seen very close to the sea shore. Haloxylon salicornicum dominate in these areas along with Acacia tortilis, Fagonia mollis, Capparis decidua and Stipagrostis plumosa. Small water channels and runnels originate along the slopes and reach the sea. During rainy season, silt accumulates in small ditches along the slopes and provide habitats for a diverse herbaceous flora comprised of Aizoon canariense, Arnebia hispidissima, Bassia muricata, Blepharis ciliaris, Caylusea hexagyna, Cucumis prophetarum, Diplotaxis harra, Fagonia bruguieri, Launaea capitata, Trigonella hamosa, Zilla spinosa and Zygophyllum simplex (Tetraena simplex).
Flora of Northern Tihama Acanthaceae Blepharis ciliaris Justicia flava Aizoaceae Aizoon canariense Mesembryanthemum nodiflorum Amaranthaceae Aerva javanica Amaranthus graecizans Amaranthus hybridus Amaranthus viridis Anabasis setifera Arthrocnemum macrostachyum Atriplex farinosa Bassia muricata Bienertia cycloptera Chenopodium glaucum Chenopodium murale Digera muricata Halocnemum strobilaceum Halopeplis perfoliata Haloxylon salicornicum Salsola imbricata Salsola lachnantha Salsola spinescens Salsola volkensii Seidlitzia rosmarinus Suaeda aegyptiaca Suaeda monoica Suaeda vermiculata Amaryllidaceae Pancratium maximum Apiaceae Anisosciadium lanatum Deverra triradiata Apocynaceae Calotropis procera Cynanchum acutum Leptadenia pyrotechnica Odontanthera radians Pergularia daemia Pergularia tomentosa Rhazya stricta Aracaceae Hyphaene thebaica Phoenix dactylifera Asparagaceae Asparagus falcatus Asphodelaceae Asphodelus fistulosus Asteraceae Asteriscus hierochunticus Atractylis mernephthae Centaurea pseudosinaica Centaurea schimperi Centaurea scoparia Cotula sp. Echinops erinaceus Echinops erinaceus Echinops polyceras Echinops viscosus Ifloga spicata Iphiona scabra Launaea capitata Launaea intybacea Launaea massauensis Launaea mucronata Launaea procumbens Picris babylonica Picris cynocarpa Pluchea ovalis Pulicaria guestii Pulicaria jaubertii Pulicaria undulata Reichardia tingitana Senecio flavus Sonchus oleraceus Boraginaceae Arnebia hispidissima Echium horridum Gastrocotyle hispida Heliotropium aegyptiacum Heliotropium arbainense Heliotropium bacciferum Heliotropium curassavicum Heliotropium europeam Heliotropium rariflorum Trichodesma africanum Brassicaceae Anastatica hierochuntica Anastatitica heirochuntica Diplotaxis acris Diplotaxis harra Diplotaxis harra Eremobium aegyptiacum Eremobium aegyptiacum s. lineare Eremobium lineare Erucaria hispanica Farsetia aegyptia Farsetia longisiliqua Farsetia longisiliqua Farsetia stylosa Farsetia stylosa Morettia parviflora Morettia parviflora Notoceras bicorne Sisymbrium erysimoides Zilla spinosa Capparaceae Cadaba farinosa Cadaba glandulosa Cadaba oblongifolia Capparis decidua Capparis sinaica Cleome amblyocarpa Cleome brachycarpa Cleome glaucescens Cleome noeana Cleome viscosa Dipterygium glaucum Maerua crassifolia Caryophyllaceae Gymnocarpos decandrum Gypsophila capillaris Paronychia arabica Polycarpaea repens Polycarpaea robbairea Pteranthus dichotomus Sclerocephalus arabicus Silene linearis Spergula fallax Convolvulaceae Convolvulus fatmensis Convolvulus glomeratus Convolvulus hystrix Convolvulus pilosellifolius Cressa cretica Cuscuta campestris Cuscuta planiflora Seddera latifolia Cucurbitaceae Citrullus colocynthis Cucumis prophetarum Cymodoceaceae Cymodocea rotundata Cyperaceae Cyperus conglomeratus Ephedraceae Ephedra foliata Ephedra aphylla Euphorbiaceae Andrachne telephioides Chrozophora oblongifolia Chrozophora tinctoria Euphorbia cuneata Euphorbia granulata Euphorbia retusa			Gentianaceae Centaurium spicatum Geraniaceae Erodium deserti Erodium laciniatum Erodium touchyanum Monsonia nivea Juncaceae Juncus rigidus Lamiaceae Lavandula coronopifolia Lavandula pubescens Otostegia fruticosa Salvia aegyptiaca Salvia deserti Salvia deserti Teucrium leucocladum Teucrium polium Leguminosae Acacia ehrenbergiana Acacia gerrardii Acacia hamulosa Acacia johnwoodii Acacia oerfota Acacia origena Acacia raddiana Acacia tortilis Astragalus fatmensis Astragalus schimperi Astragalus vogelii v. fatmensis Crotalaria aegyptiaca Indigofera coerulea Indigofera oblongifolia Indigofera spinosa Lotus corniculatus Prosopis juliflora Psoralea plicata Retama raetam Senna alexandrina Senna italica Taverniaria spartea Tephrosia nubica Trigonella hamosa Trigonella stellata Loranthaceae Plicosepalus curviflorus Malvaceae Abutilon pannosum Abutilon pannosum Abutilon sp. Hibiscus micranthus Malva parviflora Malva verticillata Subfamily-Grewioideae Corchorus depressus Corchorus olitorius Grewia mollis Grewia tembensis Grewia tenax Menispermaceae Cocculus pendulus Molluginaceae Glinus lotoides Gisekia pharnaceoides Neuradaceae Neurada procumbens Nitrariaceae Nitraria retusa Nyctaginaceae Boerhavia diffusa Orobanchaceae Cistanche phylepaea Plantaginaceae Kickxia pseudoscoparia Plantaginaceae Plantago amplexicaulis Plantago ciliata Plantago ovata Plumbaginaceae Limonium axillare Poaceae Aeluropus lagopoides Aristida adscensionis Cenchrus ciliaris Centropodia forsskalei Cymbopogon schoenanthus Cynodon dactylon Desmostachya bipinnata Dichanthium annulatum Enneapogon desvauxii Eragrostis barrelieri Hyparrhenia hirta Lasiurus scindicus Panicum turgidum Paspalidium desertorum Pennisetum divisum Poa annua Schismus barbatus Sporobolus spicatus Stipa capensis Stipagrostis ciliata Stipagrostis plumosa Polygonaceae Calligonum comosum Rumex vesicarius Resedaceae Caylusea hexagyna Ochradenus baccatus Oligomeris linifolia Reseda decursiva Reseda sphenocleoides Rhamnaceae Ziziphus spina-christi Rhizophoraceae Rhizophora mucronata Salvadoraceae Salvadora persica Scrophulariaceae Kickxia aegyptiaca Solanaceae Datura innoxia Lycium shawii Solanum glabratum v. sepicula Solanum incanum Solanum sepicula Tamaricaceae Tamarix aucheriana Tamarix nilotica Urticaceae Forsskaolea tenacissima Verbenaceae Avicennia marina Xanthorrhoeaceae Asphodelus fistulosus Zygophyllaceae Fagonia bruguieri Fagonia glutinosa Fagonia indica Fagonia mollis Fagonia schweinfurthii Fagonia tristis Seetzenia lanata Tribulus pentandrus Tribulus terrestris Zygophyllum album Zygophyllum coccineum Zygophyllum fabago Zygophyllum hamiense var. qatarense Zygophyllum simplex
Page written, designed and maintained by Dr. Jacob Thomas Pandalayil, Herbarium (KSU), King Saud University, Riyadh, Saudi Arabia.