Description from Flora of China
Cypripedium purpuratum Lindley, Edwards’s Bot. Reg. 23: ad t. 1991. 1837; Cordula purpurata (Lindley) Rolfe; Cypripedium sinicum Hance ex H. G. Reichenbach; Paphiopedilum aestivum Z. J. Liu & J. Yong Zhang; P. purpuratum var. hainanense F. Y. Liu & Perner; P. sinicum (Hance ex H. G. Reichenbach) Stein.
Plants terrestrial. Leaves 4-6, distichous; blade pale green and carinate abaxially, distinctly or obscurely tessellated with dark and light green adaxially, narrowly elliptic or suboblong, 9-15(-17) × 2.3-4.2 cm, acute and slightly tridenticulate at apex. Scape erect or suberect, terminating in a solitary flower; peduncle purple-violet, 9-19 cm, white pubescent; floral bract narrowly ovate-elliptic, 1.7-2.5 × 0.7-0.9 cm, ciliate, abaxially white pubescent particularly on midvein; pedicel and ovary 4-6 cm, pubescent. Flower 8-10 cm in diam.; dorsal sepal white, with broad maroon veins, greenish toward base; synsepal white with green veins; petals glossy purple-maroon, veined with dark purple, tinged with greenish or yellowish toward base and apex, and spotted with blackish maroon in basal half; lip purple-maroon, greenish on back of pouch; staminode pale yellow-purple, with 2 green-veined blotches on both sides of whitish center. Dorsal sepal broadly ovate, 3-4 × 3-4.2 cm, abaxially puberulent, minutely ciliate, acuminate at apex; synsepal ovate to ovate-lanceolate, 2-3.5 × 0.9-1.6 cm, abaxially puberulent, minutely ciliate, acuminate at apex. Petals suboblong, 3.5-5 × 1-1.4 cm, blackish ciliate, with blackish maroon spots somewhat wartlike, acute or unequally bilobulate at apex; lip helmet-shaped, 3.5-4.5 cm, verrucose on incurved lateral lobes; pouch 2-3 × 2.2-2.8 cm, outside minutely warty. Staminode lunate, 7-8 × 10-11 mm, puberulent adaxially, with inwardly pointed lateral lobes and an acute tooth at apex. Fl. Jun-Dec. 2n = 40.
Rocky places in forests or thickets along valleys; 100-1200 m. S Guangdong, S Guangxi, Hainan, SE Yunnan [N Vietnam].