Flower:

One-sided raceme of 5 to 20 pairs of drooping, elongated pea-shaped flowers. Flowers are ½ to ¾ inch long, the upper petal (standard) flaring upward, lateral wings below it oval, extending outward, as long as the standard is high. The standard is typically pink to deep purple with lighter colored lateral wings though sometimes all flowers in a cluster are all white. The calyx holding the flower is swollen at the base and covered in spreading hairs, as are the flower stalks.

Leaves and stems:

Leaves are compound with 8 to 12 pairs of leaflets, and a branched tendril at the end that entwines surrounding vegetation for support. Leaves can be up to 10 inches long and 2 inches wide but 6 inches or less is typical. Leaflets are about 1 inch long and ¼ inch wide, toothless, hairy, generally elliptical. Stems are viney, multi-branched and sprawling, with distinct ridges and covered in spreading hairs.

Fruit:

Pods are flat-sided up to 2 inches long, each producing several round seeds.

Notes:

A historical forage introduction, this aggressive legume has spread widely in east central Minnesota and is a common purple flower in the landscape along roadsides and fields, forming dense mats of tangled stems. Walking through a patch of it can be like trudging through a jungle. As like any flower it has some aesthetic value but for the human mind only, it is of marginal forage need to larger herbivores and provides poor wildlife habitat with little or no insect productivity while spreading easily in higher grade native habitats. It is likely highly under reported in Minnesota. A similar species is Cow Vetch or Bird Vetch (Vicia cracca), which is mostly hairless with slightly smaller flowers that are often all the same color. Cow Vetch is also a perennial where Hairy Vetch is mostly an annual.