Habenaria dilatata (Pursh) Hook.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.
Species Description - Stout or slender, to 1 m; lowest lf bladeless; principal foliage lvs lanceolate or lance-linear, to 20 × 4 cm, the upper smaller and passing into the bracts; spike 1–3 dm, dense or open; bracts narrowly lanceolate, the lowest 1.5–4 cm; fls erect or appressed, white; lip 6–8 mm, blunt, lance-ovate, conspicuously widened at base; lateral pet lance-ovate, falcate, directed forward and incurved under the upper sep; spur slender, as long as the lip; 2n=42. Bogs and wet woods; Iceland and Greenl. to Alas. and ne. Asia, s. to N.Y., Pa., O., Io., N.M., and Calif. (Platanthera d.)
tall white bog-orchid