Subfamily Vanilloideae Szlach., Fragm. Flot: Geobot. SlIppI., 3,48 (1995).
Terrestrial, perennial, monopodial or sympodial, sometimes achlorophyllous, mycotrophic vines or herbs. Roots elongate, typically fleshy, fibrous or swollen into tubers, used for climbing when produced aerially; velamen, if present, uniseriate or of Calanthe-type. Stem upright, glabrous, sometimes hollow, sometimes elongate and climbing.
Leaves one or many, alternate or: whorled, often fleshy or coriaceous with prominent reticulate venation, sometimes absent and reduced to scale-like bracts. Inflorescence a single terminal flower, terminal or axillary raceme, or, panicle; rachis pubescent in same species.
Flowers mostly showy, resupinate, subtended by a bract, with abscission layer between ovary and perianth, sometimes with a distinct calyculus beneath perianth; variably fragrant. Sepals free, glabrous or externally: pubescent, mostly fleshy and spreading, yellow, white, green, pink, or brown. Petals free, glabrous, fleshy or membranaceous, spreading or incurved, sometimes arching forward to form a false floral tube, usually subequal to sepals, yellow, white, pink, green, or brown. Labellum free or with lateral margins fused to column, forming a floral tube, simple or more often trilobed, variously ornamented with complex, multicellular hairs, bristles, mobile scales, papillae or crests, sometimes with a pair of glands at the base.
Column usually slender, glabrous, sometimes arched; stigma usually emergent; rostellum often acute and bent forward; column apex frequently hooded, typically with a pair of distinct, broad or slender, denticulate appendages on either side of the anther; anther terminal, hyper incumbent, mobile, sometimes with a pair of forward-pointing projections; pollen mostly loose, shed in monads, sometimes tetrads, or rarely forming true pollinia without accessory structures. Ovary unilocular or trilocular, glabrous or pubescent, sometimes prominently ribbed.
Fruit a capsule or rarely a fleshy, indehiscent berry.