Plants 35-105 cm. Leaves 2-5, spreading to ascending, scattered along stem, gradually reduced to bracts distally; blade lanceolate, elliptic, oblong-elliptic, or oblance-oblong, 7-27 × 1.2-5 cm. Spikes lax to dense. Flowers resupinate, showy, rose-purple; lateral sepals somewhat reflexed; petals oblong-linear to spatulate, distally crenate to entire; lip descending to somewhat porrect, deeply 3-lobed, without basal thickening, 11-20 × 12-23 mm, distal margins of lobes dentate-lacerate, rarely nearly entire, lateral lobes narrowly cuneate, middle lobe broadly cuneate-flabellate, emarginate to 2-fid; spur clavate, 20-30 mm; rostellum lobes directed forward, spreading, angular; pollinaria straight to geniculate; pollinia directed forward; viscidia orbiculate; ovary slender, 13-23 mm. Flowering (Jun--)Jul--Aug(--Oct). Alluvial forests, wet wooded flats, stream banks, seeping slopes, marshes, moist prairies, old fields and pastures, ditches, thickets; 0--800 m; Ala., Ark., Del., Ga., Ill., Ind., Ky., Md., Miss., Mo., N.J., N.C., Ohio, Pa., S.C., Tenn., Va., W.Va.
From Flora of Indiana (1940) by Charles C. Deam
This species is not infrequent in our southern counties in low, flat woods, usually associated with beech and sweet gum and pin oak. It has also been reported from Monroe County. Usually rather frequent where found.
Stem 3-10 dm; lower 2-4 lvs lanceolate, 10-20 cm; upper lvs abruptly reduced, lance-linear; infl 6-18 נ4-6 cm, rather loose; fls reddish-purple; sep broadly oval or obovate, 6-10 mm; lateral pet ca equaling the sep, obovate-spatulate above a narrow base, erose; lip 13-22 mm, deeply tripartite, the terminal lobe deeply notched, each lobe broadly cuneate- flabellate, with conspicuous radiating veins, erose at the margin, the teeth only 0.5-1 mm deep; spur 22-31 mm. Open, swampy or vernally wet places, often in acid soil; N.J. to O. and Mo., s. to S.C., Miss., and Ark. July, Aug. (Blephariglottis p.; Platanthera p.)
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.