Stapelia hirsuta stems are subquadrangular in cross-section, about 20 centimetres (7.9 in) high, and 1 centimetre (0.39 in) to 2 centimetres (0.79 in) thick. Concave groves run vertically along the stems, between their four angles. This feature can sometimes help to distinguish S. hirsuta from many other Stapelia species with which it naturally co-occurs (e.g. Stapelia rufa, Stapelia engleriana) that typically have stems which are also subquadrangular, but which are more rounded in cross-section. The surface of S.hirsuta stems are also usually shortly pubescent. Leaf rudiments are 1-2mm long. Populations growing on sandstones can be glabrous stemmed, stemmed with purple mottling. Stapelia hirsuta flowers are flat, very hairy, dark-red and resemble rotting meat. Corolla can reach a width of about 5–15 centimetres (2.0–5.9 in). The carrion smell serve to attract various pollinators, especially flies. The flowering period extends from late summer through late autumn.