Plants 15-65 cm. Roots few-several, spreading to descending, mostly to 0.75 cm diam., slender to stout. Leaves, basal, spreading, obovate, 2-5 × 1-2 cm. Spikes secund to tightly spiraled, 8-10 flowers per cycle of spiral; rachis glabrous to sparsely pubescent, trichomes capitate to clavate, glands obviously stalked. Flowers white; sepals somewhat spreading, distinct to base, elliptic, 5 × 1 mm; lateral sepals white throughout, apex acuminate; petals lanceolate, slightly oblique, 5 × 1 mm; lip white with green or yellowish green center, ovate to oblong, 5 × 2.5 mm, apex dilated, its margin crisped-crenate, pubescent; veins obscure; basal calli erect, short-pointed, mostly to 1 mm; viscidium linear-lanceolate; ovary mostly 3 mm. Seeds monoembryonic.
Slender, 1-4 dm; basal lvs ovate-elliptic or ovate- lanceolate, petiolate, spreading to form a rosette (but sometimes withering early), 1-6 נ0.6-3 cm; cauline sheaths (3)4-7, essentially bladeless; infl 3-15+ cm, its axis sparsely and minutely glandular-hairy especially upwards (hairs 0.1-0.2 mm), the fls in a single loose or compact spiral, spreading or somewhat declined, subcylindric, small, 3.5-6.5 mm, white except for the large green central spot on the lip; lip broadly oblong, erose at the rounded-subtruncate summit, its basal callosities 0.5-1 mm, higher than thick; 2n=30. Open, sandy places, often with pines; N.S. and N.B. to Sask., s. to Fla. and Tex. Two ill-defined vars. with broadly overlapping range: Var. lacera, with loose infl, lvs persistent at anthesis, and fl early (July), is northern, s. to Va., Tenn., and Mo. Var. gracilis (Bigelow) Luer, with denser infl, lvs withered by the time of anthesis, and fl late (Aug., Sept.) is southern, n. to s. N.H., c. Vt., s. Wis., and Nebr. (S. gracilis)
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.