Habit: herbs, often epiphytic
Leaves: alternate or all basal, simple, sheathing, sometimes succulent and attached to swollen fleshy stem (pseudobulb)
Plants: synoecious (rarely polygamous or monoecious)
Inflorescence: spike, raceme, panicle, solitary
Flowers: perfect, zygomorphic
Sepals: 3, distinct or connate, petaloid or green
Petals: 3, distinct or connate, 2 similar, one a labellum--saccate or spurred
Stamens: 1 or 2 (rarely 3), wholly adnate to stigma and style forming a column, anthers with pollen grains in pollinia, pollinia sometimes covered by a rostellum
Ovary: 3 connate carpels, ovary inferior with 1 locule and very many tiny parietal ovules, style 1, massive
Fruit: capsule with millions of tiny seeds