Trichodiadema in Z. Sukkulentenk. 2: 187. 1926 sec. Niesler (2001)
The genus includes 32 species and is divided into two subgenera (Hartmann & Niesler 2013). The latter study as well as earlier studies appear to be largely based on the types of Trichodiadema (Niesler 1997), since very little additional material (none from a South African Herbarium) is cited as the basis for their taxonomic conclusions. Distribution ranges for the recognized species remain uncertain due to the lack of cited vouchers. In addition, monophyly of the genus needs to be re-investigated in view of the fact that it was found nested among species of Delosperma (Klak & al. 2013).