The expensive orchid of the florists' trade is usually the large cattleya; species of this genus ( Cattleya ) are epiphytic plants native to tropical America. Among the other cultivated orchids are several of the terrestrial rein orchids (genus Habenaria ) and many epiphytic tropical genera, e.g., the Asian Dendrobium, with pendant clusters of flowers; Epidendrum, represented in the SE United States by the greenfly orchid; and Odontoglossum, indigenous to the Andes Mts.
About 140 species of orchid are native to North America, usually as bog plants or flowers of moist woodlands and meadows. Species of lady's-slipper, or moccasin flower ( Cypripedium ) [Lat., = slipper of Venus], include the pink-blossomed common, or stemless, lady's-slipper ( C. acaule ) and the showy lady's-slipper ( C. reginae ), both of the Northeast, and varieties of the yellow lady's-slipper ( C. calceolus ), which grow in all but the warmest regions of the continent. Other terrestrial genera that grow as American wildflowers are the fringe orchids ( Blephariglottis ); the small-blossomed twayblades (species of Liparis and Listera ); the pogonias, or beard-flowers ( Pogonia ); the wild pinks, or swamp rose orchids ( Arethusa ), of northeastern sphagnum bogs; the grass pinks ( Limodorum ) of eastern bogs and meadows; and the ladies'-tresses, or pearl-twists ( Spiranthes ), with a distinctive spiral arrangement of yellowish or white flowers. The coral-roots ( Corallorhiza ), named for the corallike branching of their underground rhizomes, are a nongreen saprophytic genus which includes some North American species. Because orchids are characteristically slow growing and difficult to seed, excessive picking and futile attempts to transplant have depleted native species in some areas.