Millets are a group of highly variable small-seeded grasses, widely grown around the world as cereal crops or grains for both human food and fodder. They do not form a taxonomic group, but rather a functional or agronomic one. Millets are important crops in the semi-arid tropics of Asia and Africa (especially in India, Nigeria, and Niger), with 97% of millet production in developing countries.
The crop is favored due to its productivity and short growing season under dry, high temperature conditions. The height of the pearl millet plant may range from 0.5 to 4 metres. The pearl millet grain has great variation, and can be nearly white, pale yellow, brown, grey, slate blue or purple. The kernel shape has five different classifications: obovate, hexagonal, lanceolate, globular, and elliptical.
Grains of pearl millet are about 3 to 4 mm long, much larger than those of other millets. The seeds usually weigh between 2.5 and 14 mg, with a typical mean of 8 mg. The size of the pearl millet kernel is about one-third that of sorghum. The relative proportion of germ to endosperm is higher in pearl millet than in sorghum.
The height of finger millet plant ranges from 40 cm to 1 metre, with the spike length ranging from 3 to 13 cm. The colour of finger millet grains may vary from white through orange-red, deep brown, purple, to almost black. The grains are smaller than those of pearl millet. The typical mean weight of finger millet seed is about 2.6 mg.