Fls 4-merous; hypanthium tubular at anthesis, becoming urceolate in fr, the basal part distended by the developing capsule, the terminal part persisting as a tubular or flaring neck crowned by the persistent sep; lower part of the hypanthium weakly adnate to the lower part of the ovary, easily separated from it, and becoming free at maturity; anthers unilocular at anthesis, each opening by a single terminal pore, in most spp. (not R. petiolata) elongate-linear, curved, and prolonged at the base 0.5-1 mm below and internal to the filament-tip; connective with a short, fragile, spur-like appendage externally at the base; fr a capsule; seeds cochlear; perennial herbs with handsome lavender-purple to white fls in terminal cymes, appearing in late summer; lvs sessile or short-petioled, mostly 3-veined, rather remotely setose-ciliate (sometimes subserrulately so); herbage often beset with long, gland-tipped bristly hairs. 12, e. N. Amer. Spp. 3-6 frequently hybridize when at the same level of ploidy.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.