Leaves are composed of 4 to 10 paired leaflets, terminate with a tendril, and usually are smooth. Leaflets are broader and appear more succulent than those of hairy vetch. Common vetch has a taproot that can reach depths of 3 to 5 feet. Common vetch flowers from April to May and ripens seed from mid- to late June. Flowers are violet-purple or sometimes white.
Seeds are brownish, dull gray, or black.
Unlike hairy vetch, common vetch is not hardseeded and therefore is less likely to become a weed problem if plants escape at field edges or go to seed before incorporation. The winter growth rate of common vetch is intermediate and is greater than that of hairy vetch in western Oregon. In general, however, growth is slow during cool weather, and rapid in warm spring temperatures. Environmental preferences and limitations Common vetch is moderately resistant to cold. It is likely to winter-kill in eastern Oregon.