Actually, millet is not a single genus, but an agricultural name, referring to a group of several quite distinct genera.
The following are the top 3 millet, ordered by how widely grown, plus a millet that is not widely grown but I ate as a child. In the botanic names in the parenthesis are in the format of (genus species). As you can see, the 4 millet belong to 4 different genera. The grains look similar, but the plants look very different.
1) Pearl millet (Pennisetum glaucum) (Chinese: 御谷)
It originated from south of Sahara. It is now grown in India and Africa. Pearl millet can grow in areas of drought, low soil fertility, high salinity, and high temperature. It can be grown in areas where other cereal crops, such as maize or wheat, would not survive.
2) Foxtail millet (Setaria italica) (Chinese: 粟, 小米) It has the longest history of cultivation among the millets, having been grown in China since 8,000 years ago. Its early maturity and efficient use of available water make it suitable for raising in dry areas.
3) Proso millet (Panicum miliaceum) (Chinese: 黍，黄米) It originated from China. It is now grown in Russia and China. In the US, it is used as bird feed. The water requirement of proso is probably the lowest of any major cereal. It is an excellent crop for dryland and no-till farming. It tolerates dry soil and hot wind. It can be grown in areas where other cereal crops, such as maize or even foxtail millet, would not survive.
4) Job's Tears (Coix lacryma-jobi) (Chinese: 薏苡) When I was a child, I had porridge made of this rare millet. I thought it was tasty. It is also considered as folk medicine.
