20. Cypripedium japonicum Thunberg in Murray, Syst. Veg., ed. 14. 817. 1784.
扇脉杓兰 shan mai shao lan
Cypripedium cathayanum S. S. Chien.
Plants 35-55 cm tall, with a relatively slender, creeping rhizome 3-4 mm in diam. Stem erect, brown tomentose, with several sheaths in lower part and 2 subopposite or rarely 3 nearly alternate leaves near middle. Leaf blade flabellate, 10-16 × 10-21 cm, both surfaces hairy toward base, with many radiating veins reaching margin of apical half, base subcuneate, margin undulate, minutely ciliate. Inflorescence terminal, with 1 flower; peduncle brown tomentose; floral bracts foliaceous, rhombic or ovate-lanceolate, 2.5-5 × 1-2(-3) cm, glabrous, minutely ciliate; pedicel and ovary 2-3 cm, densely hairy. Flowers pendulous; sepals and petals greenish yellow, base ± spotted with purple; lip yellowish pink to whitish, ± marked with purplish red spots and stripes. Dorsal sepal narrowly elliptic or narrowly elliptic-lanceolate, 4.5-5.5 × 1.5-2 cm, glabrous, apex acuminate; synsepal similar to dorsal sepal, 4-5 × 1.5-2.5 cm, apex shallowly 2-lobed. Petals obliquely lanceolate, 4-5 × 1-1.2 cm, villous toward adaxial base, apex acuminate; lip pendulous, pouched, subellipsoid or obovoid, 4-5 × 3-3.5 cm, strongly grooved-margined around mouth. Staminode elliptic, ca. 10 × 6-7 mm, base shortly auriculate. Capsule subfusiform, 4.5-5 × ca. 1.2 cm, sparsely puberulent. Fl. Apr-May, fr. Jun-Oct. 2n = 20.
Moist and humus-rich soils in forests, thickets, forest margins, shaded slopes; 1000-2000 m. Anhui, S Gansu, Guizhou, Hubei, Hunan, Jiangxi, S Shaanxi, Sichuan, Zhejiang [Japan].