Orchidaceae

Abstract

Orchidaceae, commonly known as the orchid family, one of the two largest families (another is Asteraceae), in the order of Asparagales, is a family of monocotyledonous flowering plants, including about 763 genera, consisting of approximately 28,000 known species, cosmopolitan distribution, except for polar or desert regions. Plants are usually perennial herbaceous, with rhizomes. They are sympodial or monopodia, leafy, and sometime vestigial to bract-like scales. Leaves are solitary to numerous. Flowers are often zygomorphic, bisexual, and arranged to racemose, spicate, or paniculate. Sepals are usually free. Petals are free and rarely adnate. Gynostemium. Ovary s inferior, usually 1-loculed, and sessile or pedicellate. Placentation parietal. Stigmas are 3-fid. Fruit is a capsule and longitudinally dehiscent. Seeds are exalbuminous. Only one species, Spiranthes sinensis (Pers.) Ames, is illustrated in this chapter.