Habenaria clavellata (Michx.) Spreng.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.
Species Description - Slender, 1–4 dm; foliage lf 1, near or just below (seldom well below) the middle of the stem, linear-oblong to narrowly elliptic or oblanceolate, 7–16 cm, up to 3 cm wide; upper lvs 1–few, much reduced; infl open, 2–6 cm, the narrowly lanceolate bracts shorter than the 5–15 fls; fls divergent, white or tinged with green or yellow, twisted to one side so that the spur is lateral; lip broadly cuneate, 3–5 mm, shallowly (sometimes obscurely) 3-lobed at the summit; sep and lateral pet broadly ovate, 4–5 mm; spur 7–12 mm, strongly curved, dilated at the tip; 2n=42. Acid bogs and wet soils, especially in sphagnum; Nf. to Ont. and Minn., s. to Fla. and Tex. June–Aug. (Platanthera c.)