General: erect perennial, hairless, 15-100 cm tall, the stem leafy, from fleshy, tuber-like roots.
Leaves: alternate, gradually reduced upward, sheathing, the lower ones from oblong-elliptic to lanceolate, blunt-tipped or pointed, mostly 4-10 cm long and 1-3 cm broad, sometimes up to 25 cm long and 5 cm broad, upward on the stem more pointed.
Flowers: white to slightly greenish-tinged, very fragrant, many in a tall, dense spike, 5-30 cm long, with bracts at bases. Sepals lanceolate, blunt-tipped, mostly 3-nerved, the upper one broader, hooded, 4-6 mm long, the lower 5-8 mm long, spreading, usually twisted. Petals lanceolate, the upper ones bent inward, 1- or 2-nerved, equalling or slightly exceeding the upper sepal and touching it, forming a distinct hood. Lip 5-8 mm long, 5- to 7-nerved, distinctly broadened at the base, the tip rounded. Spur slenderly cylindric to club-shaped, curved, from half to as long as the lip. Pollen sacs only slightly separated.