Orchidaceae

                               (Cronquist, 1981)
Strongly mycotrophic, terrestrial or often epjphytic perennial herbs, sometimes climbing, usually green and photosynthetic, but some terrestrial Soo. Without chlorophyll, and 3 Australian Soo. Wholly subterranean, plants apparently always with raphides on some of the cells, and often with mucilage-cells, commonly with crassulacean acid metabolism, and often producing one or another sort of alkaoid, but only occasionally saponiferous or some what tanniferous, and not cyanogenic, vegetative organs commonly storing starch, the grains sometimes compoud, vessels with scalariform or simple perforations, often present in the roots, seldom also on the stems, rarely even in the leaves, plastids of the sieve-tubes with cuneate proteinaceous inclusions, epjphytic Spp. With modified serial roots, the epidermis proliferated into a spongy, water absorbing velamen usuallys several cells thick, stem-base especially on epiphytic spp. Often thickened to form a pseudobulb, but terrestrial spp. Commonly rhizomatous or with secondary growth. leaves alternante (sometimes distichous) or seldom opposite or whorled, sometimes all Basal, or reduced to mere scales, simple and entire, variously convolute or conduplicate in aestuvation, parallel-veined often somewhat fleshy, sheathing at the base, the sheath nearly always closed, stomates paracytic or less often anomocystic, seldom tetracytic. Flower borne in racemes, spikes, or panicles, generally individually subtended by a bract, or sometimes solitary on the leaf-axils or on a scape, perfect or seldom unisexual,epigynous, commonly but not always resupinate, usually very strongly irregular and bilaterally symmetrical, but virtually regular in the Apostasioideae, perianth typically of 6 tepals in 2 series, all petaloid, or the sepals sometimes Greener and more foliaceous in texture, sepals all alike, or the median one somewhat unlike  the other two on form or color, or two or all three sepals connate. The family Orchidaceae as here broadly defined consist of up to 1000 genera and 15-20.000 species