Orchidaceae

=Family description=
 * Epiphytic or terrestrial herbs, rarely vines**, sometimes hemi- or holoparasitic on fungi (so called 'saprophytic orchids', leafless and achlorophyllous terrestrials), often with aerial roots provided with a velamen (water-absorbing tissue of empty cells in several layers, white when dry), the stems frequently swollen (pseudobulbs).
 * Leaves** simple, sometimes reduced to scales, alternate, rarely opposite or whorled, often in two rows, frequently thick and leathery, usually sheathing basally; margin entire or rarely serrulate, very rarely lobed (not in Asia). Stipules absent.
 * Inflorescences** terminal or lateral, paniculate or racemose, sometimes reduced to a solitary flower.
 * Flowers** usually bilateral symmetric, bisexual, exceptionally unisexual, plants then monoecious, functionally dioecious or polygamous. Tepals 6, those of the outer whorl (sepals) mostly almost equal, but not rarely distinctly unequal, free or variously connate. Tepals of the inner whorl (petals) unequal, the median one free, transformed into a variously shaped, often calliferous and sometimes spurred lip (labellum), the lateral ones free or rarely adnate to the sepals. Stamens 3, 2, or mostly 1, connate with the style into a column. Two-staminate forms often with a staminode (modified sterile anther). Unistaminate forms with the anther firmly attached to the base of the column or with the anther lying in a dorsal hollow and then with an often easily detached anther-cap; the pollen forming tetrads, usually arranged into 2, 4, 6, or 8 discrete bodies (pollinia), these mostly forming part of a specialized pollen transfer mechanism often of rather complicated structure (pollinarium), sometimes pollen gel-like or powdery and not forming discrete pollinia. Ovary inferior, 1-locular or rarely 3-locular, apical part of the style in two- and three-staminate forms free, stigma 1, 3-lobed, in unistaminate forms the stigma usually a cavity below the apex of the column, facing the lip, with one lobe more or less modified into a wall like or protruding structure (rostellum) separating the anther from the fertile part of the stigma.
 * Fruit** a dry capsule, very rarely a berry. Seeds many, usually minute, almost always lacking endosperm.

=General info=
 * Distribution** Cosmopolitan, predominantly in the tropics. About 24000 species in 800 genera; in Southeast Asia c. 6500 species in 240 genera.
 * Ecology** The seedlings of almost all orchids are mycotrophic, they will fail to develop in the absence of a certain fungus. Many orchids show highly specialised pollination mechanisms, but our knowledge of the Southeast Asian species in this respect is grossly inadequate. Many epiphytic species, while terrestrial forms usually specialise on specific habitats like bare rock-surfaces. Most common at higher elevations, especially cloud forests.
 * Uses** Many ornamentals; //Vanilla planifolia// (vanilla flavouring).
 * Similar to** Orchids are the only monocots with pollinia, but the relatively few orchid taxa that lack pollinia may be recognised by the combination of two or three fertile anthers with zygomorphic flowers.

=Treated genera=
 * Dendrobium
 * Paphiopedilum

Dendrobium sp

Paphiopedilum Orchids are the only monocots with pollinia, but the relatively few orchid taxa that lack pollinia may be recognised by the combination of two or three fertile anthers with zygomorphic flowers.