| Digitaria exilis, Digitaria iburua|
Fonio is the term for two cultivated grains in the Digitaria genus which are notable crops in parts of West Africa. The grains are very small. The crops have C4 metabolisms and are medium in height. The number of chromosomes for the species can be diploid (2n), tetraploid (4n), or hexaploid (6n).
The name (borrowed by English from French) is from Wolof foño.
White fonio, D. exilis, also called "hungry rice," is the most important of a diverse group of wild and domesticated Digitaria species that are harvested in the savannas of West Africa. Fonio has the smallest seeds of all species of millet. It has potential to improve nutrition, boost food security, foster rural development, and support sustainable use of the land.
Fonio has continued to be important locally because it is both nutritious and one of the world's fastest-growing cereals, reaching maturity in as little as six to eight weeks. It is a crop that can be relied on in semi-arid areas with poor soils, where rains are brief and unreliable. The grains are used in porridge and couscous, for bread, and for beer.
The small grains make it difficult and time-consuming to remove the husk. Traditional methods include pounding it in a mortar with sand (then separating the grains and sand) or "popping" it over a flame and then pounding it (which yields a toasted-color grain; this technique is used among the Akposso). The invention of a simple fonio husking machine offers an easier mechanical way to dehusk.
Black fonio, D. iburua, is a similar crop grown in Nigeria, Niger, Mali, Guinea, Togo, and Benin, Ghana
According to the mythology of the Dogon people of Mali, among whom it is known as pō tolo, the supreme creator of the universe, Amma, made the entire universe by exploding a single grain of fonio, located inside the "egg of the world".