Appearance: Annual or short-lived perennial herbaceous plants. Their weak stems grow 2 - 3' high and clamber over other vegetation, smothering it. The stem of hairy vetch has spreading hairs.
Leaves: Alternate, pinnately compound (leaflets on both sides of a common stalk); 8 -12 pairs of narrow oval-shaped opposite leaflets.
Flowers: Violet-blue on cow vetch and blue and white on hairy vetch. They are clustered on one-sided spikes and bloom from May to August.
Seeds: Seeds are contained in numerous inch long pods. Pods of cow vetch are brownish lance-shaped and flat; pods of hairy vetch are gray to black and hairy.
Roots: Both plants have a 1- 3' long taproot.