Liliidae: Orchidales. 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.
Each "thumbnail" image below is linked to a larger photograph.
|Cypripedium sp. (Cypripedioideae). One sepal of the outer perianth whorl is uppermost in the flower. The other two sepals are scarcely visible behind the two similarly colored petals of the inner whorl. The third petal is highly modified and forms a pink pouchlike labellum at the bottom of the flower. The column is colored similar to the petals and has a flap on each side where each of the two stamens are attached.|
|Paphiopedilum sp. (Cypripedioideae). A broad, green and white striped sepal is at the top of the flower. Two red speckled petals extend left and right. The third petal is very highly modified and forms the large pouch-like labellum at the bottom of the flower. The column is green and white, extending from the center of the flower. One stamen is adnate to the lower surface of each of the greenish lobes of the column. A portion of one of the two smaller green sepals is visible just to the right of the column.|
|Dendrobium sp. (Orchidoideae). In this orchid all of the perianth segments are of the same color and texture. One of the petals is modified into a labellum. Opposite the labellum is a three-angled pink and whitish column with a bright yellow stamen at the top. A pair of orange pollinia are partly exposed on the side facing the labellum (left photo). In the flower on the right, the 2-lobed anther and pollinia have been removed, leaving a pair of depressions in the top of the column.|
|Cattleya sp., a very showy genus commonly seen in corsages.|
|Stelis cf. argentata (Orchidoideae). These tiny flowers have 3 brownish outer perianth segments and 3 greenish inner ones. One of the inner segments forms a miniature pouchlike labellum. The column is yellowish.|
|Orchis latifolia (Orchidoideae). This attractive terrestrial orchid is native to the French Alps.|
|Orchis ustulata (Orchidoideae). This is a terrestrial orchid found in the French Alps.|
|Anoectochilus sandvicensis, jewel orchid (Orchidoideae). This is the showiest of the three species of orchids endemic to the Hawaiian Islands.|
|Liparis hawaiensis, 'awapuhiakanaloa (Orchidoideae). This tiny green flowered species is one of only three orchids that are endemic to the Hawaiian Islands.|
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