An erect herb 10-80 cm tall, more or less densely glandular hairy throughout, often forming clumps, with short stout creeping rhizomes with fibrous roots. Erect stems terete, leafy above, covered by three more or less pubescent tubular sheaths below. Leaves pleated strongly, many-nerved, three to five (rarely six), elliptic to ovate or ovate-lanceolate, acute to acuminate, 5-20 cm long, 2.1-10 cm wide, somewhat two-ranked, sheathing the stem below, bright green, pubescent above and below on veins, ciliate. Inflorescence one- or two-flowered; rhachis terete, glandular hairy; bracts leaf-like, ovate-lanceolate, acuminate, 2.9-10 cm long, 0.8-4 cm wide, pubescent and ciliate. Flowers medium-sized to large, showy, the sepals and petals yellow or greenish usually suffused and streaked with rusty brown or dull brown, tIle lip yellow with ma.. genta spots and streaks within, the staminode yellow with red spotting; pedicel and ovary 2-3.2 cm long, reddish glandular hairy. Dorsal sepal suberect to porrect, lanceolate, acuminate, 2.5-7(-8.5) cm long, 1.4-3.5 cm wide, often undulate and slightly spirally twisted. Synsepal similar but bidentate at apex, 2.3-8 cm long, 1.4-2.5 cm wide, incurved behind lip and with lateral margins somewhat reflexed. Petals spreading-deflexed at 45 to 60° below horizontal, spirally twisted one to three times, rarely untwisted, linear-tapering, acuminate, 3-7(-9) cm long, 0.5-1 cm wide, pubescent on mid-vein and at base within. Lip ellipsoidal, obovoid or subreniform, with a small mouth, 2-5.2 cm long, 1.5-2.5 cm wide; apical margins incurved, incurved sides with a pleat on each side at the base. Column short, c. 1 cm long; staminode subsessile, concave towards apex, conduplicate, triangular-ovate, blunt, 1-1.2 cm long, 0.7-1 cm wide; filaments extending beyond anthers, subacute.
A plant of rich woods growing in heavy damp humusrich but well-drained soils in partial shade, also on rocky hillsides, along streams, in meadows and clearings, in shallow turfy depressions on treeless limestone barrens and plateau in peaty soil, and in talus of limestone cliffs. It thrives in limestone areas, but the soils are usually neutral to slightly acidic; sea level to 2000 m. Flowers from May to July depending on latitude, habitat, climate, and soils.
Canada (from the Yukon and British Colombia across to the eastern seaboard and Newfoundland), U.S.A. (from southeastern Alaska, Washington and Oregon across to the eastern seaboard and south to Louisiana, Texas, New Mexico and Arizona). Common in the eastern parts of its range but rarer in the west and south.