long. Black fonio (Digitaria iburua) is taller and may reach 1.4 m. It has 2-11 subdigitate racemes up to 13 cm long.
Although both species belong to the same genus, crossbreeding them seems unlikely to yield fertile hybrids, as they come from different parts of the same genus.17
The grains of both species range from "extraordinarily" white to fawn yellow or purplish. Black fonio's spikelets are reddish or dark brown. Both species are more-or-less nonshattering.
Fonio is grown as a cereal throughout the savanna zone from Senegal to Cameroon. It is one of the chief foods in Guinea-Bissau, and it is also intensively cultivated and is the staple of many people in northern Nigeria. Fonio is not grown for food outside West Africa.
There are no formal cultivars as such, but there are a number of recognized landraces, mainly based on the speed of maturity.
Flowering is apparently insensitive to daylength.
Fonio is extremely tolerant of high rainfall, but not—on the whole—of excessive dryness. The limits of cultivation (depending on seasonal distribution of rainfall) are from about 250 mm up to at least 1,500 mm. The plant is mostly grown where rainfall exceeds 400 mm. By and large, the precocious varieties are cultivated in dry conditions and late varieties in wet conditions.
Although fonio is grown at sea level in, for instance, Sierra Leone, the Gambia, and Guinea-Bissau, its cultivation frequently is above 600 m elevation.
It is grown mainly on sandy, infertile soils. It can, however, grow on many poor, shallow, and even rocky soils. Most