Trifolium dubium Sibth.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.
Species Description - Much like no. 16 [Trifolium campestre Schreb.]; stalk of the terminal lfl scarcely 1 mm; heads smaller, 5–10 mm, commonly with 5–15 fls each 2.5–3.5 mm; standard inconspicuously veined; 2n=28, 32. Native of Europe, established as a weed in waste ground throughout much of N. Amer. Summer.