Gen. Sp. Orchid. Pl., 291. 1835.
Plants 8–110 cm. Leaves 2–several, spreading to ascending, scattered along stem, rather abruptly to gradually reduced distally; blade linear-lanceolate, ovate-lanceolate, elliptic-lanceolate, 5–35 × 1–5 cm. Spikes dense to rather lax. Flowers resupinate, showy, white; lateral sepals reflexed; petals linear to oblanceolate, apex fringed to nearly entire; lip reflexed to porrect, without basal thickening, ovate-oblong to oblong-elliptic, rarely quadrangular-suborbiculate, margin fringed; spur essentially cylindric, slender; rostellum lobes curving forward, slightly spreading, angular-elongate; pollinaria with stalks curved forward; pollinia remaining enclosed in anther sacs; viscidia elliptic-suborbiculate to orbiculate; ovary slender, 10–28 mm.
e North America.
Varieties 2 (2 in the flora).