Epiphytic herb to 50 cm tall. Sterns rhizomatous. Leaves sub-linear, to 45 cm long, 4 cm wide; apex minutely trifid, oblique. Inflorescence a 2-3 flowered, spicate raceme to 50 cm tall. Peduncle finely pubescent, green. Floral bracts 7.5 cm long, 3.5 cm wide, shorter than the ovary; inner surface sparsely covered with tiny glandular hairs; margins entire; apex obtuse. Sterile lower bracts absent. Flower in most ways like P. caudatum, whitish-yellow suffused with red-brown; outer surfaces puberulent; inner surfaces glabrous. Dorsal sepal elliptic-ovate, 10.5-11.0 cm long, 2.7-2.8 cm wide, 11-13 nerved; outer surface pubescent; margins white; apex acute. Synsepal elliptic-ovate, 9.0-10.2 cm long, 3.3-3.5 cm wide, 17-19 nerved; margins white, finely pubescent to glabrous; apex acute. Labellum 5 cm long, labellar opening oval; apical labellum rim finely pubescent; lateral labellum rim ciliate with yellow-brown hairs, spurs absent; claw face white with red-brown splotches; claw interior pubescent. Petals linear-elongate, 25-45 cm long, to 1.4 cm wide, white, pendant and strongly spiralled; veins green basally, red apically; inner surface finely pubescent; basal hairs white, multicellular; margins ciliate with multicellular purple hairs; apex long-acuminate. Staminode absent. Column white. Filaments elongate, white with red smudges. Pollinarium ovoid, in contact with sides of stigmatic surface. Stigmatic surface white, lobes rounded, white with red smudge. Ovary, including pedicel, 12-15 cm long, finely pubescent, green, curving abruptly at the apex. Capsule 11.5 cm long, 5 mm in diameter, pubescent, brown. Seeds dark brown. Chromosome number unknown.