Staples, G.W. & Herbst, D.R. (2005) A Tropical Garden Flora; plants cultivated in the Hawaiian islands and other tropical places. Bishop Museum Press, Honolulu, Hawaii.
Description of the genus
Perennial succulents; stems trailing with internodes between leaves; base becoming woody. Leaves opposite, finger-shaped and 3-angled, joined at the base. Flowers terminal, solitary, showy; calyx 5 lobed. Ovary inferior. Fruit fleshy, indehiscent. Seeds obovoid on long thread-like stalks.
Worldwide: 25 species, main South Africa (from SW Cape to KwaZulu-Natal), 4 in Australia and naturalised elsewhere.