Included here are the arid, lowland areas in and around Somalia and Ethiopia.

Somalo-Ethiopian Acacia-Commiphora Deciduous Bushland

These bushlands form the climax vegetation over much of this zone. They are often dense and can reach heights of 5 m with scattered emergent trees up to 9 m. In places they forms an impenetrable thicket made more so by many spiny species. In fact, all of the dominant Acacias and many of the Commiphoras are covered in spines. Although there is considerable variation in floristic composition, species of Acacia, Commiphora, Grewia and Capparidaceae are nearly always present. Characteristic taxa of the canopy include Acacia bussei, A. mellifera, A. nilotica subsp. subalata, A. reficiens subsp. misera, A. thomasii, Commiphora africana, C. boiviniana, C. campestris, C. erythraea, C. mollis, C. schimperi, Balanites orbicularis, Boscia coriacea, Boswellia neglecta, Cadaba farinosa, Cassia abbreviata, Cordia ovalis, Dobera glabra, Euphorbia scheffleri, Hymenodictyon parvifolium, Lannea alata, Sesamothamnus rivae, Platycelyphium voense, Premna hildebrandtii, Salvadora persica, Sterculia africana, and endemics such as Givotia gosai (Euphorbiaceae), Terminalia orbicularis, T. parvula (of the Combretaceae) and Thylachium thomasii (Capparaceae).  Common smaller bushes and shrubs include Bauhinia taitensis, Bridelia taitensis, Caesalpinia trothae, Combretum aculeatum, Carphalea glaucescens, Ecbalium amplexicaule, Ephretia teitensis, Grewwia fallax, and the endemic Caucanthus albidus (Malpighiaceae), Erythrochlamys spectabilis (Acanthaceae), Maerua denhardtiorum (Capparaceae), Sericocomopsis hildebrandtii and S. pallida (Amaranthaceae).  Succulents are scattered throughout with the candelabra-like Euphorbia robecchii being one of the more characteristic species, while in some areas the cactiform Euphorbia grandicornis forms local thickets. Other stem succulents include Adenia obesum, Monadenium inventustum and the endemic Calyptrotheca somalensis and C. taitensis (Portulacaceae). There are also a number of succulent climbers such as Cissua quadrangularis and Sarcostemma viminale with their succulent, photosynthetic stems, Cissus rotundifolia with succuent leaves, while Adenia globosa and Pyrenacantha malvifolia have immense water-storing tubers of up to 1 m in diameter. Other common climbers include Gerrardanththus lobatus, Kedrostis gijef, Pergularia daemia and Thunbergia guerkeana. These bushlands are extemely rich in endemic species with at least 230 occurring throughout the BioProvince, which includes at least 17 endemic species of Acacia, 29 endemic species of Aloa and 39 endemic species of Commiphora. However, many of the endemic species are quite localized and often confined to limestone and/or gypsum.

Examples of endemic species found in this habitat throughout the zone include trees such as Albizia obbiadensis, Cordyla somalensis, Dalbergia commiphoroides, Dichrostachys kirkii, Dicraeopetalum stipulare, Lonchocarpus kanurii Senna baccarinii (Fabaceae), Boscia mazzocchii (Capparaceae), Boswellia rivae (Burseraceae), Euphorbia giumboensis, E. jatrophoides (Euphorbiaceae), Farsetia somalensis (Brassicaceae), Hildegardia gillettii (Sterculiaceae), Kirkia tenuifolia (Kirkiaceae), Lannea malifolia (Anacardiaceae), Moringa ruspoliana (Moringaceae), Turraea barbata (Meliaceae), shrubs such as Abutilon anglosomaliae, Gossypium frifurcatum, Hibiscus bricchettii, Pavonia eremogeiton, Sida ogadensis (Malvaceae), Acacia somalensis, Arthrocarpum somalense, Bauhinia leucantha, Caesalpinia oligophylla, Calliandra gilbertii, Cordeauxia edulis, Crotalaria incrassifolia, Dalbergia varandensis, Indigofera boranica, Microcharis nematophylla, Ormocarpum muricatum, Parkinsonia raimondoi, Rhynchosia gansole, Senna ruspolii, Tephrosia obbiadensis (Fabaceae), Basanthe berberoides (Passifloraceae), Bottegoa insignis (Ptaeroxylaceae), Calyptrotheca somalensis (Portulacaceae), Cissus ellenbeckii (Vitaceae), Commicarpus mistus (Nyctaginaceae), Commiphora horrida (Burseraceae), Dasysphaera alternifolia, Lopriorea ruspolii, Pupalia robecchii (Amaranthaceae), Euphorbia cryptospinosa, Jatropha dichtar (Euphorbiaceae), Eureiandra somalensis (Cucurbitaceae), Farsetia robecchiana (Brassicaceae), Grewia penicillata (Tiliaceae), Gyrocarpus angustifolius (Hernandiaceae), Halothamnus somalensis (Chenopodiaceae), Harmsia sidoides, Melhania hiranensis (Sterculiaceae), Kelleronia gillettiae (Zygophyllaceae), Limeum angustifolium (Molluginaceae), Loewia glutinosa (Turneraceae), Maerua candida (Capparaceae), Oxygonum altissimum (Polygonaceae), Polygala effusa (Polygalaceae), Triumfetta actinocarpa (Tiliaceae), climbers such as Adenia aculeata (Passifloraceae), Caucanthus albidus (Malpighiaceae), Cissus aphylla, Cyphostemma cornus-africani (Vitaceae), Cucumis hastatus and  Dactyliandra stefaninii (Cucurbitaceae), Rhynchosia megalocalyx, Tylosema argentea, Wajira albescens (Fabaceae), and herbaceous species such as Amorphophallus laxiflorus, Stylochaeton grandis (Araceae), Aneilema somaliense, Cyanotis somaliense (Commelinaceae), Anthericum jamesii, Chlorophytum applanatum (Anthericaceae), Brachiaria breviglumis, Eragrostis psammophila (Poaceae), Cleome gallaensis (Capparaceae), Farsetia longistyla, Matthiola erlangeriana (Brassicaceae), Indigofera davensis, Senna humifusa (Fabaceae), Kalanchoe subrosulata (Crassulaceae), Polygala bariensis (Polygalaceae), Psilotrichum gracilipes (Amaranthaceae), Reseda ellenbeckii (Resedaceae) and Sida floccosa (Malvaceae).                        

Somalo-Ethiopian Evergreen and Semi-Evergreen Bushland

These bushlands are usually confined to the dryer slopes of mountains often forming an ecotone between montane forest, especially juniper forest, and the lowland Acacia-Commiphora bushland. Some of the best examples can be seen on the slopes of the Ethiopian Highlands. Although there is considerable variation in species composition, Carissa edulis, Dodonaea viscosa, Olea africana and Tarchonanthus camphoratus are nearly always present together with species of Acokanthera, Euclea, Sanservieria, Teclea and succulent species of Aloe and Euphorbia. On the Kedong escarpment nearNairobi they form an almost impenetrable thicket with a canopy up to 7 m high. The dominant crown species are Acokanthera schimperi, Euclea divinorum, Gnida subcordata, Olea africana, while other large bushes commonly include the endemic Canthium keniense (Rubiaceae). The cactoid stem-succulent Euphorbia candelabrum occurs as scattered emergents up to 9 m tall. The shrub layer typically comprises Aspilia mossambicensis, Psiadia arabica, Tinnaea aethiopica and Turraea mombassana, while the few climbers commonly include Capparis fascicularis, Pterolobium stellatum, Senecio petitians and Scuta myrtina.  Apart from succulents, such as species of Crassula, Kalanchoe and Sansevieria, the ground layer is usually sparse, but may include shade tolerant grasses like Ehrharta erecta. In Somalia the principal bushes are Acokanthera schimperi, Buxus hildebrandtii, Cadia purpurea and Dodonaea viscosa, while other important species include the endemic Aloe eminens (Asphodelaceae) and Rhus somalensis (Anacardiaceae). Throughout these bushlands many more endemic species may be encountered including trees such as Acacia manubensis and Ceratonia oreothauma subsp somalensis (Fabaceae), Dovyalis verrucosa (Flacourtiaceae), Grewia truncata (Tiliaceae), Steganotaenia commiphoroides (Apiaceae), shrubs such as Diplolophium somaliense (Apiaceae), Fagaropsis hildebrandtii (Rutaceae), Hibiscus ahlensis (Malvaceae), Indigofera sedgewickiana, Ormocarpum somalensis (Fabaceae), Jatropha variablis (Euphorbiaceae), Maerua intricata (Capparaceae), Maytenus punctata, M. somalensis (Celastraceae), Melhania engleriana (Sterculiaceae), Polygala somaliensis (Polygalaceae), Rhus puccionii (Anacardiaceae), Thilachium thomasii (Capparaceae), Uvaria denhardtiana (Annonaceae), succulents such as Euphorbia fascicaulis and E. gillettii (Euphorbiaceae), and herbaceous species such as Chlorophytum petraeum (Anthericaceae), Crassula volkensis (Crassulaceae), Crotalaria leucoclada (Fabaceae), Eragrostis trachyantha (Poaceae), Pelargonium glechomoides (Geraniaceae), Polygala amboniensis (Polygalaceae), Rosifax sabuletorum (Amaranthaceae) and Zehneria somalensis (Cucurbitaceae).

References

Brenan, J. P. M. 1978. Some aspects of the phytogeography of tropical Africa. Annals of the Missouri Botanical Garden, 65: 437-474.

McGinnies, W. G. et al. (eds). 1970. Deserts of the World. The University of Arizona Press.

Mwaura, F. & Kaburu, H. M. 2009. Spatial variability in woody species richness along altitudinal gradient in a lowland-dryland site, Lokapel Turkana, Kenya. Biodiversity and Conservation, 18: 19-32.

Thulin, M. (ed). 1993. Flora of Somalia. Vol. 1. Gymnospermae; Angiospermae (Annonaceae - Fabaceae). Royal Botanic Gardens Kew.

Thulin, M. (ed). 1995. Flora of Somalia. Vol. 4. Angiospermae (Hydrocharitaceae - Pandanaceae). Royal Botanic Gardens Kew.

Thulin, M. (ed). 1999. Flora of Somalia. Vol. 2. Angiospermae (Tiliaceae - Apiaceae). Royal Botanic Gardens Kew.

White, F. 1983. The Vegetation of Africa. UNESCO.