Medium sized epiphyte. Leaves 4 or 5, strap-like, to 40 cm long, to 4 cm wide, yellow-green. Flowers solitary, to 15 cm wide; winter and spring. Dorsal sepal obovate, larger than laterals, green, yellowish or white with purplish streaks or blotches. Petals spoon-shaped, slightly narrower than dorsal sepal, margins wavy, brownish with darker veins. Labellum helmet-shaped, colour similar to petals. Several varieties are recognised that vary mostly in the shape and colour of the dorsal sepal.

India, Burma and Thailand.

var. villosum has an almost flat dorsal sepal, which is green with purplish streaks and blotches.

var. boxallii (Rchb. f.) Veitch has a yellow and white, dark-blotched dorsal sepal with the lower margins curved strongly backwards.

Source: Jeanes, J. (2005). Orchidaceae. In: Spencer, R.. Horticultural Flora of South-eastern Australia. Volume 5. Flowering plants. Monocotyledons. The identification of garden and cultivated plants. University of New South Wales Press.