Arching shrub 1-3 m; bark of young twigs brown, exfoliating the second year; lvs ovate to oblong, 4-8 cm, toothed or entire, acuminate, rounded to acute at base, glabrous, or very sparsely hairy beneath; fls in cymules of 3 or solitary, 3.5-5.5 cm wide; hypanthium, pedicels, and outer side of sep glabrous; styles separate above; seeds long-tailed; 2n=26. Streambanks and moist hillsides or cliffs, chiefly in the mts.; e. Pa., Va. and Tenn., Ga. and Ala., sometimes escaped from cult. northward. May, June. (P. grandiflorus)
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.