The various millet species can be divided into two broad categories: pearl millet and "small" millets. The latter group, with the exception of proso millet, have smaller grains than pearl millet.
Pearl millet (Pennisetum glaucum, P. typhoides, P. tyhpideum, P. americanum) is the most widely grown of all millets. It is also known as bulrush millet, babala, bajra, cumbu, dukhn, gero, sajje, sanio or souna.
Pearl millet is a traditional crop in Western Africa, particularly in the Sahel; in Central, Eastern and Southern Africa; and in Asia, in India and Pakistan and along the southern coast of the Arabian peninsula.
Pearl millet has been recently introduced as a grain crop in the southeastern coastal plain of the United States, where it has been used as a summer forage. Pearl millet can be grown on poor, sandy soils in dry areas that are unsuitable for maize, sorghum or finger millet. It is a summer cereal grass with large stems, leaves and heads. It is more efficient in its utilization of moisture than sorghum or maize.
The grain grows on condensed panicles (spiked) 10 to 150 cm in length. Pearl millet has the highest yield potential of all millets under drought and heat stress.
Finger millet (Eleusine coracana), known as ragi in India, is another important staple food in Eastern Africa and in Asia (India, Nepal). It has a slightly higher water requirement than most other millets and is found in cooler, elevated regions up to 2000 metres above sea level. The plant carries several spikes or "fingers" at the top of the stem. The grain is small (1-2 mm in diameter).
Proso or Common millet
Proso or Common millet (Panicum miliaceum) is grown in temperate climates. It is widely cultivated in the Russian Federation, the Ukraine, Kazhakastan, the United States, Argentina and Australia. The plant has open, branching, drooping panicles and is tolerant of a wide range in temperature.
Foxtail millet (Setaria italica) is also adapted to moderate climates. It produces long, cylindrical or lobed, bristly, condensed panicles. China ranks first in the production of foxtail millet in the world. It is grown there for both food and feed. The crop is also grown in India, Indonesia, the Korean peninsula, and some parts of southern Europe. It is not grown to any extent in Africa outside the eastern highlands. Prior to the availability of sorghum-sudangrass forage hybrids, foxtail millet was an important temporary pasture species.
Teff (Eragrostis tef) is a very small-seeded grass that is cultivated for grain in the Ethiopian highlands, where its production exceeds that of most other cereals. It tolerates heavy soils with poor drainage characteristics. Several of its relatives are highly valued forage grasses in the world's arid zones.
White fonio (Digitaria exilis), Black fonio (Digitaria iburua), and Guinea millet (Brachiaria deflexa) are minor cereals of dry areas in sub-Sahelian Western Africa. White fonio is cultivated throughout much of this region, except Liberia. It is a very important crop in southern Mali, northeastern Nigeria, extreme southern Niger, western Burkina Faso, eastern Senegal and northern Guinea. Black fonio is found in isolated pockets in the Jos-Bauchi plateau of Nigeria and the northern parts of Togo and Benin. Guinea millet cultivation is confined to the Fouta-Djallon plateau of Guinea and Sierra Leone.
There are several other "minor" millets, some of which are of regional importance.
Barnyard millet (Echinochloa crusgalli, E. colona) is important in the tropics and subtropics of India.
Little millet (Panicum sumatrense) is widely grown in India, Nepal, Pakistan, Sri Lanka, eastern Indonesia and western Myanmar.
Kodo millet (Paspalum scrobiculatum) is harvested as a wild cereal in Western Africa and India, where it grows abundantly along paths, ditches and low spots. The species was domesticated in India about 3000 years ago.
Job's tears (Coix lachryma-jobi) is a minor cereal even among the small millets, with production confined largely to Southeast Asia.