Nodal and internodal spines commonly present; lvs 1.5-3 נ2-3.5 cm, glandular and hairy at least beneath, broadly cuneate to truncate (rarely subcordate) at base; peduncles and pedicels each 2-6 mm; bracts finely glandular-ciliate; ovary and hypanthium glabrous; hypanthium above the ovary obconic, 2.5-4 mm; sep glabrous, oblong, blunt, 2.5-4 mm; pet obovate, 2-3 mm; stamens ca equaling to slightly exceeding the pet, but shorter than the sep; fr smooth, greenish-purple; 2n=16. Moist woods; n. Mich. to Hudson Bay, w. to Alas., Wyo., and Nev. May, June. Ours is var. oxycanthoides. (R. setosum, a western phase)
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.