This vetch has been sparingly sown as a forage crop throughout the state and has escaped to roadsides and fallow fields. I found it to be frequent in 1930 in sandy soil along the river road about a mile west of Georgetown, Cass County. The landowner of the adjacent field told me that he had the field in hairy vetch 14 years before, therefore we have a record of its persistence for that length of time. Now frequent along the roadsides throughout northern Indiana.
Annual or biennial to 1 m, the stems spreading-villous, especially upwards; lfls usually 5-10 pairs, narrowly oblong to lance-linear, 1-2.5 cm; racemes long-peduncled, dense, secund, with 10-40 fls; cal irregular, villous, the tube 2.3-4 mm, very gibbous, the pedicel apparently ventral; upper lobes linear-triangular, 0.8-1.5 mm; lateral and lower lobes linear above a triangular base, the lowest 2-5 mm, long-villous; cor slender, 12-20 mm, the spreading blade of the standard less than half as long as the claw; fr 2-3 cm, glabrous; 2n=14. Native of Europe, intr. in fields, roadsides, and waste places throughout most of the U.S. and s. Can. June-Aug.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.