Thesium longifolium var. vlassovianum A. Candolle; T. vlassovianum (A. Candolle) Trautvetter [not “classovianum”].

Herbs perennial. Stems caespitose, ascending, ca. 50 cm, with evident furrows. Leaves sessile, linear, 40-45 × ca. 2.5 mm, 3-veined, base attenuate, apex acuminate. Inflorescences racemelike, usually sparsely or not branched, with 1 flower per axil; bracts inserted at top of pedicel, linear, ca. 10 mm; pedicel 6-20 mm, finely striate; bracteoles 2, narrowly lanceolate, ca. 4.5 mm, margin rugose. Perianth 5-merous, yellowish white, campanulate, 4-5 mm, lobes narrowly lanceolate, apex acute, incurved. Stamens 5, inserted on the base of lobes, not exserted. Ovary stalk ca. 0.5 mm. Style not exserted. Nutlet yellowish green, subglobose or ellipsoid, 3.5-4 mm, sometimes with forked longitudinal veins (or ridges); persistent perianth shorter than fruit; stalk not reflexed when fruit mature. Fl. and fr. Jun-Jul.

Grassy marshlands; 1200-2000 m. Heilongjiang, Hubei, Hunan, Jiangxi, Jilin, Liaoning, Nei Mongol, Qinghai, Shandong, Shanxi, Sichuan, Xizang, Yunnan [Mongolia, Russia].