Fonio (Digitaria exilis (Kippist) Stapf) also called Acha is a glumaceous monocot of the genus Digitaria of the family Gramineae (or Poaceae).

There are over 300 Digitaria species, which are sometimes grown as fodder crops. Only three or four are grown as cereals :

• In West Africa: Digitaria exilis or white fonio and Digitaria iburua or black fonio
• In Eastern Europe: Digitaria sanguinalis or large crabgrass or hairy crabgrass
• In India: Digitaria cruciata or raishan

Only Digitaria exilis is of any real importance in West Africa nowadays.

Fonio is a small annual herbaceous plant that grows to a height of 30 to 80 cm and produces inflorescences generally comprising two or three (but anything up to five) racemes. The spikelets on the racemes are grouped in pairs (early varieties) or in threes or fours (late varieties), on pedicels. The spikelets comprise a sterile flower and a fertile flower, the latter of which gives rise to the fonio grain.

Several types of varieties (or ecotypes) are distinguished:

• extra-early varieties, with a growth cycle of 70 to 90 days
• early varieties, with a growth cycle of 90 to 110 days
• intermediate varieties, with a growth cycle of 110 to 130 days, and
• late varieties, which take more than 130 days to grow

Fonio ears (© J-F Cruz, Cirad)