Alfalfa is the general name of Medicago, commonly known as cauliflower, which is a perennial flowering plant. One of the most famous is Medicago sativa as a pasture. There are many kinds of alfalfa, most of which are wild herbs.

Annual or perennial herbs, sparse shrubs, no vanilla smell. Pinnately compound leaves, alternate, stipules partially connate with petiole, entire or dentate, leaflets 3, margin usually serrated, lateral veins extending straight to the tip of teeth. Racemes axillary, sometimes capitate or solitary, with small flowers, usually pedicled; Bracts small or absent; Calyx bell-shaped or tubular, calyx teeth 5, equal in length.

Corolla yellow, purple alfalfa and other hybrids are often purple, violet blue, brown, etc., the flag petal is obovate to oblong, the base is narrow, and it is often folded back. The wing petal is oblong, and one side has a tooth tip protrusion that hooks with the auricular body of the keel petal, which is detached after pollination, and the keel petal is blunt; Stamens are dimorphic, filaments are not enlarged at the top, and anthers are of the same type.

Style short, conical or linear, slightly flat on both sides, glabrous, with the top of the column borne, ovary linear, sessile or short-stalked, ovules 1 to most. The pod is spirally twisted, kidney-shaped, sickle-shaped or nearly straight, longer than the calyx, and the back seam is often ribbed or spiny; There are seeds 1 to most. Seeds are small, usually smooth, somewhat kidney-shaped, without caruncle; The base of cotyledons unearthed from seedlings is not enlarged and has no joints.