The genera of plants within the tribe Stapelieae are all to varying degrees stem succulents. Many of the species resemble cacti, though are not closely related, as an example of convergent evolution. The stems are often angular, mostly four-angled in cross-section, but in some species there are six or more, with some species of Hoodia having more than thirty angles. In size they vary from less than 2.5 cm/1" in length to over 2 m/6" tall. The leaves are in most species reduced to rudiments, sometimes hardened and thorn-like, arranged on bumps or tubercles on the angles. Some species, however, still have recognisable leaves, most notably the Indian species Frerea indica, and some members of Tridentea. Stapeliads are most abundant in warm, dry climates. In Africa, there are two separate regi