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Although the family Crassulaceae has a very wide global distribution range, the family has definite areas of high present-day species diversity. These include the southern Africa subcontinent, Mexico, and parts of southwestern North America, Mediterranean Europe, and parts of the Orient. Five of the c. 34 genera recognised in the Crassulaceae are represented naturally in southern Africa. These genera, Adromischus Lem., Cotyledon L., Crassula L., Kalanchoe Adans., and Tylecodon Toelken, are illustrated and briefly discussed with reference to their diversity and distribution ranges in the subcontinent and beyond. To familiarise the reader with the genus-rank diversity in southern African Crassulaceae, a pictorial gallery of southern African genera, excluding Kalanchoe, in the family is presented.

Bufadienolides are cardiac glycosides that characterise members not only of the genus Kalanchoe but also of Crassulaceae subfam. Kalanchooideae as a whole. These compounds are neurotoxins and have most probably evolved as a defence mechanism against herbivores. The acute or chronic poisoning of livestock following the consumption of kalanchoe plants in southern Africa is noted, with reference to the known chemistry of the indigenous and introduced species. In southern Africa, the ingestion of members of Kalanchoe, Tylecodon, and Cotyledon by especially sheep and goats may lead to krimpsiekte, a chronic nervous disorder caused by bufadienolides. Biocultural (nonhorticultural) uses of Kalanchoe species by humans in southern Africa and elsewhere in the world are noted. It is suggested that the group is a still largely untapped resource for the discovery of potentially novel pharmaceuticals.

Fagopyrum belongs to Polygonaceae, but the determination of Fagopyrum’s generic name had undergone many modifications. Until now, Fagopyrum should be viewed as an independent genus according to the morphological, palynological, and cytological studies. The basic chromosome number of Fagopyrum is n=8. The flower is bisexual, and its perianth is white, pale red, or yellowish-green, and has five deep lobes, but isn’t accrescent. Every flower has eight stamens, among which five are inner ones and three are outer ones. The pistil consists of three carpels, which can be divided up into a prismatoidal ovary and three styles (heterostylous or homostylous), etc. The achene is prismatoidal, which is exsert from the outside of persistent perianth, either obviously or not. The embryo is situated in the center of the endosperm; the cotyledon is wide and more or less plaited. The furrows of pollen grain are perforated and rough in exine, which forms the granular pattern.