Description from Flora of China
Viola mairei H. Léveillé; V. moupinensis var. lijiangensis C. J. Wang; V. palustris var. moupinensis (Franchet) Franchet; V. paravaginata H. Hara; V. rosthornii E. Pritzel; V. vaginata Maximowicz subsp. alata W. Becker; V. vaginata var. sutchuensis Franchet ex H. Boissieu.
Herbs perennial, acaulescent, sometimes with ascending stolon to 30 cm, clustered with several leaves at top of stolon. Rhizome erect or sometimes obliquely ascending, to 15 cm, 6-10 mm in diam., densely noded, usually with brown remains of stipules and dense rootlets. Leaves basal; stipules free, brownish or light colored in upper half, ovate, 1-1.8 cm, margin remotely denticulate or entire, apex acuminate; petiole winged, 4-10 cm, to 25 cm after anthesis; leaf blade cordate or reniform-cordate, 2.5-5 × 3-4.5 cm, accrescent after anthesis and reniform, ca. 9 × 10 cm, both surfaces glabrous, sometimes slightly puberulous only along veins abaxially, base narrowly sinuate or broadly triangular, lateral auricles often involute at anthesis, margin glandular obtusely dentate, apex acute or acuminate. Flowers purplish or white, purple-striate, large; pedicels not exceeding leaves, 2-bracteolate at middle; bracteoles linear. Sepals lanceolate or narrowly ovate, apex ± acute, basal auricles short, apex truncate, remotely and shallowly dentate, margin narrowly membranous. Petals oblong, lateral ones bearded, anterior one ca. 1.5 cm (spur included); spur saccate, conspicuously longer than basal auricles of sepals, stout; spur of 2 anterior stamens ca. 1 mm, ca. 1.1 mm in diam., apex obtuse. Ovary glabrous; styles slightly geniculate forward at base, thickened in upper part; stigmas truncate, thickly margined on lateral sides and abaxially, shortly beaked in front, beak horizontal. Capsule ellipsoid, ca. 1.5 cm, glabrous, brown glandular. Seeds large, obovoid, ca. 2.5 mm, ca. 2 mm in diam., base acute, apex rounded. Fl. Mar-May, fr. May-Jul.
Wang (Bull. Bot. Res., Harbin 8(2): 20. 1988) described a yellow-flowered variety, Viola moupinensis var. lijiangensis, and stated that it differs from the typical variety in having yellow flowers. According to our examination of the type material and field work at the type locality, we consider that the flower color of the type specimens might have been wrongly recorded.
Open places at forest margins, thickets, streamsides, grassy slopes; 600-3600 m. Anhui, Fujian, Gansu, Guangdong, Guangxi, Guizhou, Hubei, Hunan, Jiangsu, Jiangxi, Shaanxi, Sichuan, Xizang, Yunnan, Zhejiang [Bhutan, India (Sikkim), Nepal].