Description from Flora of China
Blastus yunnanensis H. Léveillé, Repert. Spec. Nov. Regni Veg. 11: 300. 1912; B. mairei H. Léveillé.
Herbs or shrublets, to 30 cm tall, branched. Stems obtusely 4-sided, densely puberulous or with glandular trichomes. Petiole 2-4 cm, densely puberulous to patently villous; leaf blade ovate-lanceolate, oblong-ovate, or nearly elliptic, 6.5-11 × 2.5-4.3 cm, papery, abaxially puberulous but strigose on veins, adaxially puberulous and slightly strigose, secondary veins 2 or 3 on each side of midvein, base rounded, margin densely serrulate with each tooth having a terminal seta, apex shortly acuminate. Inflorescences terminal, umbellate, densely puberulous and slightly with glandular trichomes. Pedicel ca. 1 cm. Hypanthium purplish red, ca. 3.5 mm. Calyx lobes narrowly triangular to lanceolate, ca. 3 mm, inside densely puberulous. Petals pink, broadly ovate, 4.5-6 mm, outside only puberulous on ridge, apex acute. Longer stamens with connective minutely inflated at base. Shorter stamens with connective decurrent, inflated, forming a short triangular spur. Ovary half inferior. Fl. Sep.
● Secondary forests, valleys, stream banks, rock crevices; 600-700 m. Sichuan, Yunnan.