Crepidium is a genus of approximately 300 species of orchids in the family Orchidaceae, order Asparagales. First described in 1825 by the Dutch botanist Carl Ludwig Blume, the genus is broadly distributed across tropical regions of Asia, Australasia, and the Pacific.
Plants in this genus are evergreen and sympodial, growing mostly as terrestrial herbs on the forest floor, though a number of species are epiphytes on mossy tree trunks. The fleshy stems lie along the ground rather than growing erect. Each plant bears two or more relatively large, distinctly pleated leaves whose petioles wrap around the stem; individual leaves may persist for up to three years.
Flowers are small to tiny and characteristically non-resupinate — that is, they are not rotated 180° as in most orchids, so the labellum points upward. They are borne in a raceme along the tip of the flowering stem and come in a range of colours including green, yellow, red, brown, and purple. The dorsal sepal is typically longer than the lateral sepals, and the petals are shorter and narrower than the sepals. The labellum is erect, flat, and generally undivided, bearing two small ear-like lobes near its base. The column is short and carries two conspicuous wings. Pollination is achieved without nectar; the flowers bear two pairs of waxy yellow pollinia.
The greatest diversity of Crepidium is concentrated in New Guinea, where roughly 90 species occur. The genus is also well represented in China (17 species, 5 endemic), Southeast Asia, the Indian subcontinent, and northern Australia (5 endemic species in Queensland and the Northern Territory). Crepidium was previously treated by some authors as part of the broader genus Malaxis, but it is distinguished by its above-ground stems, broad pleated leaves, and the characteristic undivided labellum with ear-like lobes.
Etymology
The name Crepidium derives from the Latin crepida, meaning "boot," "sandal," "shoe," or "base," likely an allusion to the shape of the labellum. The genus was first formally described in 1825 by Carl Ludwig Blume in his work Bijdragen tot de flora van Nederlandsch Indië.
Distribution
Crepidium occurs throughout tropical Asia and the Pacific, with records from China, the Indian subcontinent, Southeast Asia, New Guinea, northern Australia, and numerous Pacific and Indian Ocean islands. New Guinea harbours the richest diversity with approximately 90 species, while Australia has five endemic species confined to tropical Queensland and the Northern Territory.
Ecology
Most species grow as terrestrial plants on the floor of tropical rainforests, where they favour shaded, moist conditions. A smaller number of species are epiphytic, growing on mossy tree trunks in humid forest. The genus produces no nectar; its pollination mechanism is not well documented in available sources.
Taxonomy Notes
Crepidium was formerly treated by some authors as part of the broader genus Malaxis. It is distinguished from Malaxis by having stems that lie above the ground, broad pleated leaves with petioles clasping the stem, and an undivided labellum bearing ear-like lobes — rather than the subterranean pseudobulbs and narrower leaves typical of Malaxis. The genus belongs to the tribe Malaxideae, family Orchidaceae, order Asparagales.
