Physosiphon.—A small genus allied to Stelis. P. Loddigesii has racemes of orange-coloured flowers.
Platyclinis.—These are pretty, intermediate-house Orchids, with pendulous racemes of white or yellow flowers, generally fragrant.
Pleione. See Cœlogyne.
Pleurothallis.—A large genus of elegant, dwarf-growing Orchids for the intermediate house.
Promenæa. See Zygopetalum.
Renanthera.—These showy species are natives of Tropical Asia and Malaya. They should be grown like Aërides and Vandas. R. Imschootiana is a compact, free-growing species, with showy, crimson flowers.
Restrepia.—A cool-house genus usually grown with the Masdevallias, and requiring similar treatment.
Rodriguezia.—This genus includes the species usually called Burlingtonia in gardens. Suspend the plants in the intermediate house. R. secunda has rose-coloured flowers; most of the others are white, and they are generally fragrant.
Rhyncostylis.—These are warm-house plants, which are known usually as Saccolabiums in gardens. The commoner species is R. retusa, with fine racemes of blush-white flowers, spotted with purple; and the blue R. cœlestis. The cultivation is similar to Aërides.
Saccolabium.—The Saccolabiums should be grown in a warm house like Aërides. S. bigibbum and others of its class are pretty, dwarf species, with yellowish flowers spotted with purple and having a white lip.