The African winterthorn is famous for its unusual phenology. It sheds its leaves with the rains and is green during the dry season, favoring crop production beneath its canopy and re ducing the need for a fallow period on poorer soils. Normally a deciduous tree to 15m it can reach 25m or more in southern Africa, with a large rounded crown and spreading branches, and trunk diameters of 1m or more. It is distin guished by its phenology, whitish twigs and paired thorns, blue green bipinnate leaves lacking a petiolar gland, but with glands between nearly all its 2-12 pinnate pairs. The inverted phenology does not occur in seedlings until their tap roots are well into the water table.
Flower buds appear soon after leaves on current season's growth.
Seeds are dispersed by herbivores eating the indehis cent pods or by the pods floating down rivers. It has been introduced into India, Pakistan, Nepal, Peru, Cyprus, Cape Verde and the Ascension Islands. It grows in a wide range of climates and habitats, either scattered or gregarious, in closed canopy woodland or open savanna and in cultivated lands. It is usually a pioneer on alluvial flats but can form part of a fire climax vegetation in the west African savannas, where optimal conditions are between 500-800 mm annual rainfall. In east Africa it grows well with 1800 to 8 mm or less, provided it taps underground water.