Hairy vetch is a branching, spreading annual that forms a dense ground cover. Flowers in 4-inch-long racemes on long peduncles arising from leaf axils, with 10–30 flowers of the pea type all turned to one side of stalk, in varying colors: rich lavender, purple, violet, or white. Blooms April–October. Leaves alternate, compound, ending in a tendril, with 5–10 pairs of narrowly oblong leaflets to ¾ inch long, with a point at the tip; typically hairy, though some varieties are smooth. Fruit a small pod about 1 inch long.
Similar species: There are 10 species of Vicia recorded for Missouri; about half are native, the rest introduced. Wood vetch, or pale vetch (V. caroliniana), trails or climbs, is smooth and hairless, and has white or whitish lavender flowers, with the keel petal tipped with blue or lilac. It blooms April–June and is found in rocky areas with acidic soils in the Ozarks.
Height: to 2½ feet, though it often spreads horizontally if no other plants support it.
Habitat and Conservation
Occurs in fields, waste places, roadsides and railroads, and other disturbed ground. A native of Europe, it has been much planted along highways by the Missouri Department of Transportation to prevent erosion after road construction projects.
This vetch is planted as a forage crop in pastures and in disturbed soils (such as along highways) to prevent erosion. It can be an invasive weed. As a legume, its roots add nitrogen to the ground, enriching the soil for other plants. Gardeners and farmers sometimes plant it to improve soils.
Several insects, including aphids, cutworms, earworms, grasshoppers, and weevils, consume the sap, leaves, stems, roots, or developing seeds of the plant. Many mammals, such as deer and rabbits, browse the foliage. Where this plant is invasive, it crowds out native plants and disrupts ecosystems.