A scanning electron micrograph of a root tip from a sorghum (Sorghum bicolor) plant with kidney bean shaped bacteria (Azospirillum brasilense) on its surface. Such nitrogen-fixing bacteria may live on the root surface or in the surrounding soil. The white, threadlike projections are root hairs. Sorghum bicolor, commonly called sorghum and also known as great millet, durra, jowari, or milo, is a grass species cultivated for its grain, which is used for food, both for animals and humans, and for ethanol production.