Herbs perennial, 10-30 cm tall. Stems many, erect or slightly decumbent, pubescent. Petiole ca. 1 mm, pubescent; leaf blade papery; lower leaves ovate, small; upper leaves lanceolate to elliptic-lanceolate, 1.5-3 × 0.5-1 cm, abaxially greenish, shiny, adaxially deep green, abaxially very pubescent on veins, midvein raised abaxially, impressed adaxially, lateral veins and reticulate veins raised on both surfaces, base broadly cuneate, margin recurved, apex obtuse, mucronate. Racemes opposite to leaves or extra-axillary, ca. 2 cm, to 5-7 cm at fruiting, pubescent; bracts 3, caducous, ovate-lanceolate, pubescent. Sepals 5, persistent, ciliate; outer sepals 3, elliptic, nearly equal, ca. 3 mm, 3-veined; inner sepals 2, petaloid, obovate-oblong, 5-7 × 2.5-3 mm, with 3 multibranched veins, base unguiculate, apex obtuse, mucronate. Petals 3, free, blue-purple; lateral petals oblong, ca. 3.5 mm, inside pubescent at base, margin deeply undulate, apex rounded; keel cucullate, ca. 5 mm, unguiculate, apex with small appendages. Stamens 8; filaments 3-4 mm, lower 3/4 united into an opening tube and adnate with petals, upper 1/4 free or connate; anthers ovoid. Ovary obovoid, ca. 1.5 mm in diam.; style curved, 2-3 mm; stigmas 2. Capsule suborbicular, ca. 5 mm in diam., broadly winged, apex retuse, mucronate. Seeds black, ovoid, white hispidulous; strophiole 3-lobed, ca. 2/3 as long as seeds. Fl. May-Jun, fr. May-Jul.
Type: China. Xizang: Bomi Xian, Yügong, hillside, forest understory, alt. 2400 m, 11 Jun 1973, Exped. Xizang of NW Plateau Institute of Biology, Academia Sinica 0450
(holotype, HNWP); Zayü Xian, Xia Zayü District, ridge of a rice field, alt. 1700 m, 29 Jul 1973, Exped. Xizang of NW Plateau Institute of Biology, Academia Sinica 1194
(paratype, HNWP); same locality, hillside, alt. 1800 m, 18 Jul 1973, Exped. Xizang of NW Plateau Institute of Biology, Academia Sinica 1044
Polygala japonica Houttuyn affinis, sed foliis lanceolatis vel elliptico-lanceolatis, sepalis 5, ciliis, exterioribus ellipticis, interioribus obovato-oblongis, petalis 3, discretis, filamentis supra 3/4 discretis vel connatis, carunculis trifidis differt.