Description from Flora of China
Cypripedium luteum Franchet.
Plants often 30-50 cm tall, with a stout, usually rather short rhizome. Stem erect, densely pubescent, especially near upper nodes, with several sheaths at base and 3-6 leaves above. Leaves well spaced; blade elliptic to elliptic-lanceolate, 10-16 × 4-8 cm, both surfaces pubescent, shortly ciliate, apex acute or acuminate. Inflorescence terminal, 1- or rarely 2-flowered; peduncle pubescent; floral bracts foliaceous, elliptic-lanceolate, 4-8 × 1.8-2.3 cm, pubescent; pedicel and ovary 2.5-4 cm, densely rusty hairy. Flowers yellow, sometimes tinged or flushed with red, occasionally with maroon spots on lip. Dorsal sepal elliptic to broadly elliptic, 3-3.5 × 1.5-3 cm, abaxial midvein and base sparsely puberulent, shortly ciliate, apex obtuse; synsepal broadly elliptic, 2-3 × 1.5-2.5 cm, subglabrous, apex nearly unlobed. Petals oblong to oblong-lanceolate, slightly oblique, 2.5-3.5 × 1-1.5 cm, adaxially pubescent toward base, shortly ciliate, apex obtuse; lip deeply pouched, globose-ellipsoid, 3-4.5 cm. Staminode orbicular or broadly elliptic, 6-7 × ca. 5 mm, abaxially slightly keeled, adaxially with conspicuous reticulate veins, subsessile and ± auriculate. Capsule narrowly obovoid, 3.5-4.5 cm, hairy. Fl. and fr. Jun-Sep. 2n = 20*.
● Forests, forest margins, thickets, stony places on grasslands; 1800-3500 m. S Gansu, W Hubei (Fangxian), Sichuan, SE Xizang, NW Yunnan.