About Vicia cracca L.
Cow vetch (Vicia cracca L.) is a perennial species in the legume family Fabaceae, with a growth habit similar to pea plants. It produces climbing stems that can reach 150 cm in length; individual plants may grow 2 meters long or tall, and have a white taproot that can extend up to 1 meter deep. When its leaf tips touch another plant, it grows noose-like branched tendrils that securely fasten the cow vetch to the other plant, which can strangle smaller plants. Its leaves are pinnate, 3–8 cm long, with 8–12 pairs of leaflets, each leaflet measuring 5–10 mm long. Cow vetch grows quickly and flowers prolifically. From late spring to late summer, it produces one-sided racemes that hold 10 to 40 pea-shaped purple to violet flowers, which emerge from leaf axils. Bumblebees are the main visitors to these flowers. After flowers fall, small bright green seed pods 10–20 mm long begin to develop. Mature seed pods reach 2 cm long, contain 6 to 8 seeds, and resemble the seed pods of very small peas. Seeds ripen when the pods turn black. Unripened seeds are swollen and green-tinged, and shrink as they ripen. Seed pods range from light brown to dark brown with black spots. Cow vetch is very similar to hairy vetch (Vicia villosa), but can be distinguished from hairy vetch by its smooth stem. Vicia cracca is native to Europe and Asia, and has been introduced to large areas of North America. As an introduced species, it is recorded as very frequent, occurring casually on waste ground, and also grows in hedges. Cow vetch is widely used as a forage crop for cattle. Like other legumes, it has nitrogen-fixing properties that enrich the soil it grows in, making it beneficial to other plants. It provides nectar that is valued by bees and butterflies. It can also be used to control erosion. Owners of pet birds such as budgerigars often use cow vetch as a nutritious food; the birds particularly favor the seeds, but may also eat the foliage. Its usefulness as a cover crop and source of green manure has encouraged its introduction and naturalization far beyond its native range. In North America, it has naturalized from southern Canada to upstate South Carolina. It is considered an invasive weed in some North American areas, and its sale may be regulated. Cow vetch can be a potentially harmful species in areas outside its native range, as it can crowd out native plants. It is especially likely to dominate disturbed soil before other plants can become established, which is a particular concern for prairie and other natural habitat restoration or land reclamation projects in North America.
