Fls mostly perfect; cal-tube 10-ribbed, with 5 short teeth, variously glabrous or hairy but never glandular and never inflated; pet 5, the claw narrow, usually expanded upwards into conspicuous lateral auricles at the juncture with the blade, and also generally with a pair of appendages on the inner surface at the juncture; stamens 10; styles 5, or in occasional individuals sometimes 4 or 6; capsules unilocular, or seldom largely 5-locular, dehiscent by (4)5(6) entire teeth (as many teeth as styles); seeds reniform, muricate to tuberculate; perennial herbs with opposite, entire, exstipulate lvs; x=12. 12, temp. Eurasia.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.