Bird vetch is a perennial vine in the pea family that is native to Eurasia. Pea family plants are able to fix their own nitrogen through an association with micorrhizal fungi that reside in nodules on the roots. Nitrogen fixation allows species like bird vetch to grow in areas of low fertility. This can be a desirable trait for crops, especially if they will be used as a soil building green manure.

Dense vetch grows through a chain link fence along a utility road. The plant readily uses fences to grow vertically. (UAF Cooperative Extension, University of Alaska Fairbanks, bugwood.org)

Dense vetch grows through a chain link fence along a utility road. The plant readily uses fences to grow vertically. (UAF Cooperative Extension, University of Alaska Fairbanks, bugwood.org)

Bird vetch produces many seeds that develop in pods. The seeds are relatively large, and not particularly adapted to long distance dispersal without the aid of animals or human activity. Seeds can be spread through soil, forage, or straw. Extensive seed banks can form; however, seed are only viable for up to 5 years.

In addition to seed bird vetch spreads by rhizomes, which are underground stems that grow shoots and new roots. Portions of rhizomes can spread to form new infestations when soil containing viable portions of the rhizome is moved.

Bird vetch is a Restricted Noxious Weed in Alaska. The “restricted” status means that it cannot be sold as a contaminant in seed at amounts higher than specified. However, it can be sold as bird vetch.