Plants 3-30 cm. Pseudobulbs 4-8 mm diam. Leaves 1(-2, rarely), petiolate base sheathing stem; blade light green, ovate-elliptic, keeled abaxially, 1.5-9.5 × 1-5 cm, apex acute. Inflorescences: floral bracts lanceolate, 1.5-2 mm; pedicels 2-4.5 mm. Flowers resupinate, green or greenish white; dorsal sepal ovate-lanceolate, 1.5-2.5 × 1-1.4 mm, margins revolute, apex acuminate; lateral sepals oblong-lanceolate, slightly falcate, 1.5-2.5 × 0.5-1.2 mm, apex acuminate; petals strongly reflexed, filiform to narrowly linear-lanceolate, 1.4-2.5 × 0.3-0.4 (-0.5) mm, apex rounded; lip broadly triangular, concave, 3-lobed, middle lobe ovate, apex acuminate, lateral lobes auriculate, thickened, curved upward; disc with 2 low, thickened, elongate calli, 1.3-2.2 × 1.2-1.8(-2) mm; column 0.4-0.6 × 0.4-0.6 mm. 2n = 28. Flowering summer. Swamps, bogs; 0--400 m; Alta., B.C., Man., N.B., Nfld. and Labr., N.S., Ont., P.E.I., Que., Sask., Yukon; Alaska, Calif., Colo., Ill., Ind., Maine, Mass., Minn., N.H., N.Y., Pa., Vt., Wis.