This species was discovered north of Indianapolis by W. N. Clute, May 9, 1932. He says it occurs for a mile along the old canal and along roadsides. [In a footnote Deam inserted the following ...] Clute (Amer. Botanist 45:32. 1939) says: The severe winter of 1935-36 apparently killed all the plants.
Ascending or decumbent annual; peduncles 2-5 cm; cal at maturity resembling that of no. 7 [Trifolium fragiferum L.]; cor inverted, the standard toward the lower side of the head; 2n=16. Native of Europe, intr. in grass-seed and established at widely scattered stations in our range. Early summer.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.