Eritrean coastal desert

The Aldabra Island xeric scrub covers the coral atoll of Aldabra in the Seychelles, an isolated landform in the western Indian Ocean lying roughly 400 km northwest of Madagascar. Its xeric vegetation falls into two main types: dense thickets of Pemphis acidula on the saline, low-lying ground, and a mixed scrub of low trees, shrubs, herbs, and grasses spread across most of the atoll. The climate is tropical, with an average annual temperature near 27 degrees Celsius and about 1,200 mm of rainfall, split into a wetter season from November to April and a drier stretch from May to October. The terrestrial flora includes roughly nine fern species and 178 flowering plants, of which about 38 percent are thought to be endemic. Aldabra is best known for hosting the world's largest population of giant tortoises and the flightless Aldabra white-throated rail, and the atoll has been protected as a UNESCO World Heritage Site since 1982.

The Djibouti xeric shrublands form a semi-desert belt along the Red Sea and Gulf of Aden coasts of the Horn of Africa, spanning Djibouti, Eritrea, Ethiopia, and Somalia (including Somaliland) and encompassing the Afar Triangle, a lowland that drops as much as 160 metres below sea level at fault depressions such as the Danakil and Lac Assal. Vegetation grades from coastal mangroves into open grass and shrub steppe, with thorny acacias such as Acacia (Vachellia) tortilis and Senegalia mellifera, the spiny Rhigozum somalense, and the desert date Balanites aegyptiaca characteristic of the sandy plains and basaltic lava fields. The climate is extremely hot and arid, with mean annual rainfall ranging from under 100 millimetres near the coast to around 200 millimetres further inland, and the tectonically active rift includes some of the hottest sites in Africa. The ecoregion is notable for harboring the last viable population of the African wild ass alongside the endemic Archer's lark and the dragon tree Dracaena ombet, which clings to higher arid hills. For gardeners in hot, dry climates, several drought-adapted natives here-the architectural Dracaena dragon trees and tough Acacia and Balanites genera-are familiar xeric ornamentals.

The Gariep Karoo is an arid, open shrubland in the Afrotropic realm that stretches from the middle of South Africa's Northern Cape northward across the Orange River (also called the Gariep River, which forms the border between the Northern Cape and Namibia's ǁKaras Region) into southern Namibia. Its sparse, low-shrub vegetation is dominated by succulent dwarf shrubs and tall stem-succulents including quiver trees, with characteristic genera such as Drosanthemum, Eriocephalus, Galenia, Pentzia, Pteronia and Ruschia, alongside perennial grasses like Aristida and Stipagrostis. The climate is harsh, with mid-summer maximum temperatures exceeding 36 degrees Celsius, mid-winter minimums dropping below freezing, frequent droughts, and annual rainfall between 50 and 500 millimetres that decreases from east to west. The region holds the dramatic Fish River Canyon in southern Namibia and supports the ferruginous lark, its endemic flagship bird, yet it remains poorly protected against a 40 percent conservation target. For gardeners in dry climates, its drought-hardy natives such as quiver trees and succulent shrubs in the genera Ruschia and Drosanthemum are well suited to xeric, low-water plantings.

The Hobyo grasslands and shrublands form a long, narrow coastal strip in Somalia, running along the Indian Ocean from south of Mogadishu northwards past the town of Hobyo, where a belt of wind-built dunes some 10 to 15 kilometers wide fringes the shore. The dunes carry distinctive grassland and low scrub: wind-tolerant grasses and sedges first colonize the bare sand, while denser thickets of Aerva javanica, Indigofera sparteola, and Jatropha pelargoniifolia hold the more stable ground. The climate is hot and dry, with rainfall concentrated in a short April-to-June season as the Intertropical Convergence Zone shifts north. Part of the Somali-Masai centre of plant endemism, the ecoregion shelters several species found nowhere else, including the silver dik-dik, the Somali golden mole, and the endemic Ash's lark and Obbia lark, yet it lies almost entirely outside any protected area. Gardeners working hot, sandy, low-water sites may recognize relatives of its native dune flora, such as the drought-hardy Aerva and Indigofera.

This Afrotropic desert and xeric shrubland ecoregion covers two small coralline islands, Europa and Bassas da India, a French overseas territory scattered in the Mozambique Channel about a third of the way from southern Madagascar toward southern Mozambique, with the two islands lying roughly 100 km apart. The low-lying landscape of Europa is clothed in dry forest of silver thicket (Euphorbia stenoclada), a grassy herbaceous formation of Sclerodactylon macrostachyum, coastal shrubland including bay cedar (Suriana maritima), and mangrove swamps of Rhizophora mucronata fringing a shallow lagoon open to the sea. The climate is semi-arid and tropical with wet summers and dry winters, dominated by southeast trade winds in the austral winter and the occasional cyclone. The islands are an internationally important refuge: Europa is one of the world's largest nesting grounds for green sea turtles and hosts a major great frigatebird colony along with endemic lizards and seabirds, and the area is protected as a Ramsar wetland. For gardeners, the native flora here is dominated by drought-tolerant succulent Euphorbia and salt-tolerant coastal genera adapted to heat and limited rainfall.

The Kalahari xeric savanna spans the sandy plains of the Kalahari Basin across northwestern South Africa, southern Botswana, and central-southeastern Namibia. Despite its name, it is an open, dry savanna where bunchgrasses such as Schmidtia, Stipagrostis, Aristida, and Eragrostis grow among scattered trees, most characteristically the camelthorn (Vachellia erioloba) and grey camelthorn (Vachellia haematoxylon), alongside shepherd's tree (Boscia albitrunca), blackthorn (Senegalia mellifera), and silver cluster-leaf (Terminalia sericea). The climate is harsh and continental, with patchy rainfall that rises from the dry southwest to the northeast and temperatures that can swing dramatically between cold nights and daytime highs above 40 degrees Celsius. Although plant endemism is low, the ecoregion supports a striking diversity of large mammals for such an arid system, including its flagship gemsbok along with lion, cheetah, leopard, and brown hyena. For gardeners in hot, dry climates, several of its hardy native woody plants, such as the camelthorn acacias and the shrub Grewia flava, are drought-adapted and grown ornamentally.