Description

Key Characters:

Growth Form: Terrestrial or epiphytic perennial herbs or sometimes lianas, usually green and photosynthetic but some terrestrial species lack chlorophyll and are saprophytic, rarely completely subterranean, epiphytic species with modified aerial roots and the epidermis modified into a spongy water-absorbing velamen.

Stems: Stem base or entire stem, especially in epiphytic species, often thickened to form a pseudobulb, terrestrial species often rhizomatous or with corymbs or tubers, extrafloral nectaries sometimes present on pedicels, bracts, or leaf sheaths, most species strongly associated with mycorrhiza.

Roots:

Leaves: Leaves simple. Alternate or rarely opposite or whorled, sometimes all basal or reduced to scales, especially in saprophytic species, often fleshy. Margins entire. Veins parallel. Sheathing at base the sheath usually closed. Stipules absent.

Flowers: Flowers in racemes, spikes, or panicles, or sometimes solitary in the leaf axils or on a scape, each one usually subtended by a bract. Flowers bisexual (perfect) or rarely unisexual (and then plants monoecious or dioecious), strongly zygomorphic or in subfamily Apostasioideae actinomorphic, usually resupinate (twisted during development so that the adaxial side appears to be abaxial). Sepals 3, green and foliaceous to petaloid, all similar or the median one somewhat different, sometimes 2 or all 3 sepals connate. Petals 3, the median one strongly differentiated from others, usually larger and differing in shape and also color, forming a lip (labellum), often extended to form a spur or nectary, the lateral 2 usually similar to sepals. Stamen 1(-3), all morphologically abaxial, but appearing adaxial on the opposite side from the labellum, when solitary, usually completely adnate to the style forming a column (gynostemium), the others completely repressed or occasionally represented by staminodes, when stamens 2, nearly completely adnate to the style or adnate only at base and the third stamen usually represented by an expanded staminode, when stamens 3, adnate to the style only at base; anther dithecal, the 2 thecae sometimes widely separated, opening by longitudinal slits, pollen sometimes organized into pollinia (in subfam. Orchidoideae), the members of a tetrad connected by viscid threads, the pollinia 1-6 per pollen sac, 1 end of a pollinium often prolonged into a slender tip (caudicle). Ovary inferior, 3-carpellate, 1-celled or 3-celled; ovules very numerous and minute, usually not developing until after pollination, anatropous, placentation parietal or in subfam. Apostasioideae axile; style column (gynostemium) usually stout and terminated by the solitary anther, which is subtended by an enlarged rostellum derived at least in part from the adjacent stigma lobe, often with a basal outgrowth to which the labellum and usually lateral sepals are joined; rostellum separating the anther from the 2 usually connate stigma lobes, thus preventing self-pollination, caudicles of the pollinia often attached to the rostellum, a portion of which detaches as a sticky pad (viscidium) with the pollinia when the pollen is transferred.

Fruit: Fruit usually a capsule; dehiscent by 3(6) longitudinal slits; remaining closed at apex and base. Seeds very numerous and extremely minute; embryo minute; sometimes consisting of only a few cells; cotyledon usually poorly differentiated or undifferentiated; endosperm absent; usually associated with various fungi that are necessary for germination.

Ploidy:

Habitat:

Elevation Range: