Herbs, perennial. Roots closely to widely spaced along rhizome, slender, fleshy; rhizomes short to elongate. Stems leafy or scapose. Leaves alternate, in single radical pair, or subopposite near midpoint of stem, ascending to spreading, plicate, bases sheathing stem. Inflorescences terminal, solitary; flowers solitary or 2–several in lax racemose spike; bracts large, foliaceous. Flowers resupinate, showy; sepals distinct or lateral sepals usually connate proximal to lip forming synsepal; petals entire; lip inflated, slipper- or sac-shaped, with adaxial orifice; pollinaria absent; loose granular pollen in 2 lateral anthers, dorsal anther a large subapical staminode; stigma free, 2–3-lobed. Fruits capsules, ellipsoid to oblong-ellipsoid.
Herbs, with short or long rhizomes and many thickened fibrous roots. Stem erect, elongate or short, clustered or well spaced, often with several sheaths at base. Leaves 1 to several, alternate to opposite, sometimes prostrate on substrate, sheathing and amplexicaul at base; blade adaxially green or sometimes marked with black-purple spots, often elliptic to ovate, rarely cordate or flabellate, with parallel, radiating, or 3-5 prominent veins. Inflorescence terminal, with a solitary flower or rarely many flowers; floral bracts often leaflike, usually smaller than leaves, rarely absent; ovary 1-locular. Flowers usually large and showy. Dorsal sepal erect or hooded over lip; lateral sepals usually united to form a synsepal, but free in Cypripedium plectrochilum. Petals spreading horizontally, at an angle below horizontal, or enfolding sides of lip, sometimes spirally twisted; lip deeply pouched and inflated, subglobose or ellipsoid, with incurved lateral lobes and usually also apical margin, hairy within on bottom. Column short, with 2 lateral fertile stamens, a terminal staminode above, and a stigma below; anthers 2-locular, with very short filaments; pollen powdery or glutinous; staminodes often elliptic to ovate, very rarely ligulate or linear, base stalked or not; stigma ± papillose, inconspicuously 3-lobed. Fruit a capsule.
"Sep and lateral pet somewhat differentiated, widely spreading, the 2 lower sep usually connate; lip a large inflated pouch, its margins ± inrolled around the orifice; column declined over the orifice of the lip, bearing a fertile stamen (with granular, irregularly coherent pollen) on each side and dilated staminode above; perennial from fibrous roots, the erect stem bearing 2–several basal or cauline lvs and 1 or 2 large fls. 50, N. Temp."
|Lady’s-slipper, moccasin-flower, cypripède, sabot de la Vierge [Greek Kypris, Aphrodite, and Latin pes, foot, perhaps an orthographic error for Greek pedilon, slipper]|