In recent years considerable research has been carried out on cultivated Sorghum bicolor (L.) Moench in an attempt to acquire a more complete and meaningful understanding of the taxonomy, classification, origin and evolution of Africa's most valuable cultivated crop. This work has, however, been restricted mainly to the sorghums in northern and central Africa, with southern Africa largely excluded. In this paper, the morphological variation and distribution of cultivated sorghum races in South Africa is introduced, together with comments on the classification of cultivated sorghums. A new morphological character, the groove at the base of the lower glume of mature, sessile spikelets (developed from a zone of weak, membranous tissue observable in immature spikelets) is evaluated. The degree of development of this groove varies between the different races and is considered to relate directly to their evolution and domestication.