Herbs, perennial, 30-50 cm tall; rhizomes thick. Stems erect, simple, densely villous, more sparsely so upward, densely minutely stipitate glandular. Leaves cauline, somewhat reduced upward, base sometimes marcescent, abaxially villosulous, adaxially strigillose, both surfaces minutely stipitate glandular, thin, margin serrulate to serrate, villosulous-ciliate, 3-veined, lower secondary veins prominent, apex obtuse to acute, mucronulate; lowest leaves withered by anthesis, long winged petiolate, petiole base auriculate; blade oblanceolate, base attenuate; lower to upper leaves shortly winged petiolate (base clasping) to sessile, oblanceolate to oblong, 3-8 × 0.7-1.8 cm, base rounded; synflorescence leaves lanceolate, 2-3.5 × 0.5-0.9 cm, base cuneate-rounded, margin entire. Capitula 3 or 4 or more (simple specimen) in terminal corymbiform synflorescences, rarely solitary, ca. 3 cm in diam.; peduncles 25-90 mm, strigillose to villosulous, densely minutely stipitate glandular; bracts lanceolate to linear-lanceolate, entire. Involucres broadly campanulate, 5-6(-7) × ca. 10 mm; phyllaries 3-seriate, nearly subequal, abaxially strigillose to villosulous, sparsely to densely minutely stipitate glandular, base hardened, midvein slightly translucent, distal margin and apex ± purplish; outer phyllaries linear-oblong, 4-4.6 × 0.6-0.7 mm, distal 1/2 leaflike, margin barely to ± scarious, ciliate, glandular, apex sometimes spreading or squarrose, acute, mucronulate, ciliate; middle phyllaries linear-oblong to linear-lanceolate, 5-6 × 1-1.2 mm, margin narrowly scarious, tip green or sometimes leaflike, apex acute to acuminate; inner phyllaries linear-lanceolate, 5-5.5 × ca. 1 mm, margin broadly scarious, erose, tip green, apex erose. Ray florets 23-27, blue, tube sparsely strigillose, lamina 7-9 × 1.6-2 mm, eglandular; disk florets yellow, ca. 4.5 mm, limb campanulate, ca. 3 mm, proximally sparsely strigillose and minutely stipitate glandular, lobes erect, tip sometimes spreading, narrowly triangular, ca. 1 mm, tip sparsely strigillose and minutely stipitate glandular. Achenes narrowly obovoid, ± compressed, 2.5-2.8 mm, densely strigillose, sparsely strigillose on ribs, minutely stipitate glandular apically, 2-ribbed. Pappus 3- or 4-seriate, straw-colored, of slender barbellate bristles; outermost bristles few, 0.2-0.5 mm; outer bristles absent or 1, ca. 2 mm; inner bristles 3.5-3.7 mm, tapering; innermost bristles 4.2-4.3 mm, barely clavate. Fl. and fr. Sep.

Aster trichoneurus is similar to A. auriculatus but differs in its broader and larger, 3-veined leaves without clasping auricles, and narrow, sparsely hairy phyllaries.

● Ravines, mountain canals; ca. 2700 m. NW Yunnan (Dêqên).