It is a herbaceous
annual plant, growing to tall. The
leaves are alternate and trifoliate, with three oblong or elliptical leaflets long. The distinctive yellow
flowerheads that superficially resemble
hop flowers. Each flowerhead is a cylindrical or spherical collection of 20–40 individual
flowers. The flowers become brown upon aging and drying, enclosing the fruit, a one-seeded pod.
Similar plants The species may be confused with others that have three leaflets and small yellow flowers, such as
T. aureum (large hop trefoil),
T. dubium (lesser hop trefoil),
Medicago lupulina (black medick), and
Oxalis stricta (yellow woodsorrel). == Etymology ==