Viola adunca Sm.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.
Species Description - Tufted on short or elongate rhizomes, at first anthesis erect, 2–8 cm, and nearly acaulescent, later to 15 cm and more spreading or prostrate, with evidently leafy stems; lvs darker green arid thicker than in no. 24 [Viola conspersa Rchb.], ovate to suborbicular, obtuse, crenulate, subtruncate to subcordate at base, mostly 1–2.5(–3) cm wide; stipules lance-linear, with fimbriate-incised teeth above the middle; peduncles elongate; sep narrowly lanceolate, not ciliate; pet violet, the lateral ones bearded; spur 4–6 mm, straight and blunt, or often tapering to a short, incurved point; style slender, bent at the tip; frs 4–5 mm, ellipsoid; seeds dark brown; 2n=20, 40. Sandy or gravelly, moist or sometimes dry soil; Greenl. and Lab. to Alas., s. to N.Y., Mich., Minn., and Calif. May–July. The widespread and highly variable var. adunca is ± puberulent. (V. arenaria; V. subvestita) Var. glabra Brainerd, more boreal or in our range more alpine, is essentially glabrous