Crown vetch is a perennial, herbaceous legume that reproduces by seeds and spreads vegetatively. It can form large clumps from creeping stems. The stems can be up to 6 feet long. Rhizomes can be up to 10 feet long, enabling the plant to spread rapidly. The compound leaves have 15–25 pairs of oblong leaflets. Blooms May through August. Flowers are pinkish to white and are clustered in umbels (circular, like a crown) on long stalks. Each individual flower is shaped like typical a pea flower. The fruits are narrow, flattened pods.
Similar species: Our native vetch species have vining tendrils at the ends of the stems, but crown vetch does not have any tendrils.
Height: to about 9 inches; stem length: up to 6 feet.
Widespread in Missouri, having been extensively planted on rights-of-way along interstate highways.
Habitat and Conservation
Crown vetch prefers open, sunny areas. It occurs along roadsides and other rights-of-way, in open fields, and on gravel bars along streams. It is found most easily during blooming, when its profuse pinkish blossoms are conspicuous. Animals may play a role in dispersal since some populations have turned up miles from a nearby seed source. The seeds are reported to be poisonous.
Invasive. Crown vetch can spread rapidly by seed and vegetatively by its multibranched, creeping rhizomes. The natural distribution of crown vetch is Europe, southwest Asia, and northern Africa. In the United States it occurs from Maine to South Dakota, south to Virginia, West Virginia, Kentucky, Illinois, and Missouri.
Crown vetch has been grown extensively in the northern two-thirds of the United States for temporary ground cover, erosion control, and (because it fixes nitrogen like alfalfa and other legumes) as a green fertilizer crop. It is also used as a bank stabilizer along roads and waterways.
This invasive, nonnative plant threatens our state’s biodiversity. The vegetative growth habit can rapidly cover and shade out native vegetation. A single plant may fully cover 70 to 100 square feet within four years.