Medium sized epiphyte. Stem to 20 cm long. Leaves linear, to 45 cm long, to 5 cm wide, fleshy, channelled, green. Inflorescences to 35 cm long, drooping. Flowers to 2 cm wide, fragrant, white or pink with pink or purplish markings, labellum with purplish tip; summer. Sepals ovate to oblong. Petals oblong, narrower than sepals. Labellum variable, often lanceolate, rounded or notched at tip. Spur conical, compressed, backward-pointing.

Tropical Asia.

R. coelestis (Rchb. f.) Rchb. f. from Thailand is a medium sized epiphyte with erect racemes of small (to 2 cm wide) white flowers that have bluish blotches at the tip of the sepals and petals.

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.