There are many clover-like plants that have leaves in threes, similar to alfalfa. Alfalfa is distinct in having teeth just on the upper half of the leaflets and a large dense head of purple flowers. Siberian alfalfa (Medicago falcata) has yellow flowers and fruits with straight pods. Sweetclover leaves are very similar but have teeth scattered all along leaf margins.
Alfalfa is the most important forage crop in the world and was first grown to feed livestock in Iran where it is native.Alfalfa sprouts, the sprouted seeds, are a popular salad and sandwich ingredient. Alfalfa is also used in re-vegetation and restoration projects since it provides food for wildlife as well as helping to improve soils. As with other members of the pea family, it is a nitrogen fixing plant which means that bacteria in its root nodules can take nitrogen from the air.