Botanical description and natural distribution of Andropogon gayanus

Abstract

Andropogon gayanus is a tall, tufted perennial grass that grows taller than 3 m. It forms a significant part of the vegetation of many savanna areas throughout Africa south of the Sahara, including South Africa. It is a polymorphic species which comprises four recognized botanical varieties: gayanus, tridentatus, polycladus (syn. var. squamulatus), and bisquamulatus. Of these, var. bisquamulatus is the most vigorous and well known as a useful tropical forage grass. Varieties polycladus and bisquamulatus are adapted to prolonged drought whereas the native habitat of var. gayanus is periodic swamplands. The species occurs in Africa almost exclusively between the 400 mm and 1500 mm annual isohyets and under a wide range of soil conditions. It is absent in areas with a mean minimum temperature of 4.4 oC and occurs most vigorously below an altitude of 980 m. Further research on the other three varieties, as well as on other Andropogon species, seems to be justified.