Orchidaceae Antoine Laurent de Jussieu, 1789.
Orchidaceae: Perennial, autotrophic or occasionally heterotrophic herbs, living symbiotically with endotrophic mycorrhiza. Rhizome creeping or much reduced, with fibrous, fleshy or tuber-like roots. Leaves basal or cauline, rarely absent. Stem erect, slender or robust, with terminal inflorescence. Inflorescence a few or many-flowered spike. Flowers zygomorphic, very variable in size and colour, usually resupinate. Perianth of 2 whorls: an outer whorl of 3 similar segments (sepals) and an inner with two equal segments (petals) and one unequal (labellum). Labellum ± conspicuous, highly modified in shape and colour, frequently spurred, sometimes extremely specifically adapted to certain insects, ensuring cross-pollination. Column (gynostemium or gynandrium) formed by fusion of stigmas and stamens, consisting of a central fleshy organ with a single fertile, bilocular anther and two receptive, confluent or ± separate stigmas. Anther loculi joined by a tissue (connective) which is sometimes prolonged into a beak-like or subulate process; the 2 sterile anthers (in Türkiye) obsolete or rudimentary, converted into staminodes near base on each side of column; the odd sterile stigma modified into a rostellum, separating anther from stigma. Pollinia 2, sometimes bipartite, or 4, waxy or powdery-granulose, often attached by caudicles to 1 or 2 viscid glands (viscidia) which can be free or ± enclosed in a single pouch or separately in two (bursicula), originating from parts of rostellum. Ovary inferior, sessile or minutely stalked, twisted or straight, placentation parietal; mature fruit a capsule, sometimes considerably enlarged after flowering. Seeds innumerable, tiny, without endosperm.