Iridaceae - Distribution and Habitat

Distribution and Habitat

Members of the Iridaceae are nearly worldwide in distribution, but remain rare in tropical lowlands and at high latitudes. The family is best represented in Southern Africa, especially the winter-rainfall region in the southwest. Other centers of diversity are temperate South and Central America (with several small genera) and the Mediterranean region (Iris and Crocus). About 2000 species are distributed among some 65 genera are recognized worldwide, just over half of them from Southern Africa, where 38 genera are known. In the Cape Floral Region alone, 707 species and 27 genera are recorded.

The family prefers open, seasonal habitats. In Africa, the montane grasslands of eastern South Africa, Swaziland and Lesotho, and the Succulent Karoo and fynbos of the Northern and Western Cape have the most species. Fewer species occur in savannas or the semi-arid central karoo, and very few in forests. The species grows in a variety of soils, derived from basalt, clay, dolerite, granite, limestone and sandstone, as well as rarer rocks like serpentine. Most species favor loamy soils, often among rocks where drainage is good, but some grow in marshes and others in pure sand. Species grow from just above the high tide mark to over 3,000 metres (9,843 ft) above sea level.