The lower plant stems are glabrous while the upper stems are glandular and hairy. Young seedlings often have unifoliate leaves. Leaves on mature plants are trifoliate with the lateral leaflets reduced in size compared to the terminal leaflet. The leaflets are edged with tiny teeth and are elliptical or elliptic-orbicular in shape and glabrous. The flowers are borne singly at each node, and form dense terminal spikes.
Germination occurs in the early spring.
In 1998, seedlings germinated in late March at the San Luis Obispo Co. site. Flowering begins quite soon after maturity. The plant population at the San Luis Obispo Co. site were mature and nearly ready to disperse seed in early July. The genus Ononis is large, and O. alopecuroides L. is one of several similar species in a confusing complex. Some authors consider some of these names to be synonomous with O. alopecuroides.