Much like no. 1 [Hackelia virginiana (L.) I. M. Johnst.], but averaging more slender and with smaller lvs; dorsal area of the nutlets unarmed or with only a few short prickles. Moist woods, thickets, and hillsides; circumboreal, in Amer. from s. Que. to Mack. and B.C., s. to Vt., Io., and Colo. May- Aug. (Lappula d.; L. americana; Hackelia a.) The Amer. plants are var. americana (A. Gray) Fernald & I. M. Johnst.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.