Terrestrial herb 20–75 cm tall; tubers 1–2 cm long, globose or ovoid.Stem leafy; leaves 6–14, the lowermost sometimes sheath-like, the next 6 or so large, semi-spreading, set fairly close together in lower part of stem, 6–19 × 1–2.5(3.5) cm, lanceolate; uppermost leaves grading into the bracts.Inflorescence 6–20 × 3–6 cm, fairly laxly several- to many-flowered; bracts 10–18 mm long, usually shorter than pedicel and ovary.Flowers green, white in centre, with a strong, sweet, sickly smell, especially at night.Pedicel and ovary 20–32 mm long, somewhat arched.Dorsal sepal reflexed, 5–7.5 × 3–4 mm, elliptic; lateral sepals deflexed, 7.5–10 × 5–6.5 mm, obliquely obovate with a lateral apiculum.Petals ciliolate, 2-lobed almost to base; upper lobe 5–7 × c. 1 mm, linear, erect; lower lobes pendent, hinged, 9–18 × 1.5–2.5 mm, curved lanceolate, acute.Lip 3-lobed to 1–1.5 mm from base; mid-lobe 11–20 mm long; side lobes 6.5–15 mm long; all lobes linear, c. 1 mm wide; spur 14–20 mm long with 1 twist in middle, swollen in apical half, horizontal or ± incurved.Anther c. 3 mm high, canals porrect, 4–6 mm long.Stigmatic arms 3.5–6 mm long, porrect, enlarged and truncate at apex.Rostellum mid-lobe c. 2 mm long.