67. Oncidium Swartz, Kongl. Vetensk. Acad. Nya Handl. 21: 239, plate 3, fig. Q. 1800.
[Greek oncos, swelling, and -idium, diminutive, in reference to prominent lip callus]
Mark W. Chase
Herbs, epiphytic or terrestrial, ± cespitose. Stems pseudobulbs, green, ovoid. Leaves persistent, 1–3, not recurved; blade conduplicate, linear-lanceolate, dorsiventrally flattened, margins entire. Inflorescences paniculate racemes, lateral branches to 10[–42] cm; bracts narrowly triangular. Flowers resupinate; sepals and petals distinct and free, oblong-elliptic, obovate to nearly quadrangular or nearly circular, apex retuse to obtuse, sometimes apiculate; lip pandurate, 3-lobed; callus prominent warty-tuberculate-fringed; column with wings, arms, or fingerlike projections; stigmatic cavity ± round; rostellum not prominent. Fruits capsules.
Species 800 (1 in the flora): tropical and subtropical, Western Hemisphere.
Oncidium is a large polymorphic, and probably paraphyletic, assemblage.
SELECTED REFERENCES
Chase, M. W. 1987. Systematic implications of pollinarium morphology in Oncidium Sw., Odontoglossum Kunth, and allied genera (Orchidaceae). Lindleyana 2: 8–28. Garay, L. A. and J. E. Stacy. 1974. A revision of Oncidium. Bradea 1: 393–428. Sauleda, R. P. and R. M. Adams. 1989. The orchid genera Oncidium Sw. and Tolumnia Raf. in Florida. Rhodora 91: 188–200.
