There are about 1,200 species in 62 genera, mainly found in the dry areas of Oceania and southern Africa, but also in tropical Asia and South America. It reaches as far north as Ethiopia in Africa, and as far north as the Yangtze River Basin of China and Japan in Asia. There are 4 genera in China, 2 of which are introduced and cultivated, with about 25 species distributed from the southwest to Taiwan Province.