The Orchidaceae are terrestrial, epiphytic, or saprophytic herbs comprising one of the two largest families of flowering plants with about 1,000 genera and 15-20,000 species. The leaves are alternate or seldom opposite or whorled and have a sheathing base and an entire, often fleshy, parallel-veined blade. The flowers are typically zygomorphic and bisexual but sometimes are virtually actinomorphic and rarely are unisexual. The perianth consists of 6 tepals in two similar or dissimilar whorls. The outer whorl of 3 distinct or variously connate tepals is sometimes sepaloid. Two members of the inner whorl of 3 tepals are alike and may be quite similar to the outer tepals. The third tepal of the inner whorl forms a labellum that typically is highly modified in shape and or coloration. The androecium and gynoecium are nearly always adnate into a column or gynostegium. Orchids in subfamily Cypripedioideae have two stamens, one on each side of the column. Orchids in the largest subfamily Orchidoideae have a single terminal stamen and the anthers generally produce one or more waxy masses of pollen called pollinia. The gynoecium consists of a single compound pistil of 3 carpels that together with the androecium comprises the column in most species. The stigma is just proximal to the single terminal stamen in most species. The stigma is two- or three-lobed and the ovary is inferior and almost always has 1 locule with very numerous, up to several million, very tiny parietal ovules. The fruit is mostly capsular.

Follow the links below to two of the major subfamilies of orchids.

cym_sp_fls.jpg (10946 bytes) Orchidoideae

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