Sep and lateral pet similar in color but differing in size, the pet connivent with the upper sep or with all the sep to form a concave hood over the column; lip large, prolonged at its base into a conspicuous spur; anther broadly sessile atop the column, pollen- sacs contiguous; pollinia 2; viscidia 2, enclosed in a single pouch; perennial from short rhizomes and thickened roots, the scape bearing 1 or 2 lvs near the base and a loose, terminal, few-fld raceme. 100, N. Temp.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.