Medium sized terrestrial. Leaves 4?8, narrow-elliptic, to 25 cm long, to 5 cm wide, mottled dark- and yellow-green. Flowers solitary or rarely 2, to 14 cm wide; autumn. Dorsal sepal ovate, larger than laterals, white with green veins. Petals oblong, narrower and longer than dorsal sepal, spreading, green with brownish spots. Labellum deeply helmet-shaped, mostly reddish-brown.

Thailand.

P. purpuratum (Lindl.) Stein from China is a compact terrestrial with mottled leaves, solitary whitish flowers with heavy purplish stripes and suffusions, dorsal sepal wider than petals, and a helmet-shaped labellum.

P. tonsum (Rchb. f.) Stein from Indonesia is a compact terrestrial with mottled leaves, solitary yellowishgreen to brownish flowers with stripes and spots, dorsal sepal wider than petals, and a helmet-shaped labellum.

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.