Plants solitary or in clumps, with bulbils on caudices. Leaves basal; petiole flattened, 1-9 cm; blade ovate to elliptic, 2-8 cm, ± fleshy, base attenuate, margins irregularly crenate to serrate, ciliate, surfaces sparsely to ± densely stipitate-glandular and tangled, reddish brown-hairy, adaxially glabrescent. Inflorescences 30+-flowered, (flowers sometimes secund), very open, lax, ± flat-topped thyrses, 6-50 cm, proximally hairy, distally densely purple-tipped stipitate-glandular. Flowers: sepals erect to ascending (even in fruit), ovate to triangular; petals white, not spotted, broadly oblong to elliptic, not or rarely slightly clawed, 3-6 mm, 2+ times as long as sepals; filaments linear, flattened; pistils distinct almost to base; ovary ± superior, (to 1/3 adnate hypanthium). Capsules green to purplish, folliclelike. 2n = 20 (+ 0-6 supernumeraries), 38. Flowering spring. Rocky hillsides, cliffs and shaded rock outcrops, stream banks, wooded slopes; 0-1500 m; Man., N.B., Ont., Que.; Ala., Ark., Conn., D.C., Ga., Ill., Ind., Ky., La., Maine, Md., Mass., Mich., Minn., Miss., Mo., N.H., N.J., N.Y., N.C., Ohio, Pa., R.I., S.C., Tenn., Vt., Va., W.Va. Also reported for Micranthes virginiensis is 2n = 28; D. E. Soltis (1983) documented zero to six supernumerary chromosomes in this species and speculated that this report may have included eight supernumeraries.
Flowering stems solitary or few together, 1 dm at first flowering, later to 4 dm; basal lvs oblong or ovate, 2-5 cm, entire or serrate, obtuse, cuneately narrowed to a margined petiole; infl branched, at first compact, later lax and open; hypanthium adnate to the base of the carpels; sep spreading or ascending; pet spatulate to obovate, 4-6 mm, white; seeds minutely papillate in longitudinal rows; 2n=20 + several B, 28. Moist or dry open woods and rock-ledges; N.B. to Man., s. to Ga., La., and Okla. Apr., May. (Micranthes v.) Many aberrant forms have been described.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.