黑蕊虎耳草 hei rui hu er cao

Micranthes melanocentra (Franchet) Losinskaja; M. pseudopallida (Engler & Irmscher) Losinskaja; Saxifraga atrata Engler var. subcorymbosa Engler; S. gageana W. W. Smith (1911), not Engler & Irmscher (1912); S. melanocentra f. angustispathulata Engler; S. melanocentra f. franchetiana Engler & Irmscher; S. melanocentra f. pluriflora Engler & Irmscher; S. paludosa J. Anthony; S. pseudopallida Engler & Irmscher; S. pseudopallida f. bracteata Engler & Irmscher; S. pseudopallida f. foliosa Engler & Irmscher; S. sulphurascens Handel-Mazzetti.

Stem 3.5-22 cm tall, crisped glandular villous. Petiole 0.7-3.6 cm, pilose; leaf blade rhombic-ovate or broadly to narrowly ovate to oblong, 0.8-4 × 0.7-1.9 cm, both surfaces pilose or glabrous, base cuneate, rarely cordate, margin crenate-serrate, glandular ciliate, apex subobtuse or acute. Inflorescence corymbose, 1.5-8.5 cm, 2-17-flowered; bracts ovate or elliptic to oblong, 0.5-1.5 cm × 1.1-11 mm, both surfaces glabrous or pilose, base cuneate, rarely broadly so, margin entire or dentate, apex acute. Sepals spreading to reflexed, triangular-ovate to narrowly ovate, 2.9-6.5 × 1.2-3 mm, glabrous or pilose, veins 3-8, confluent into a verruca at apex, apex obtuse or acuminate. Petals white, rarely red to purple, proximally with 2 yellow spots, or base red to purple, broadly ovate or ovate to elliptic, 3-6.1 × 2.1-5 mm, 3-9(-14)-veined, base contracted into a claw 0.5-1 mm, apex obtuse or retuse. Stamens 2.2-5.5 mm; filaments linear; anthers black. Ovary semi-inferior, dark purple, broadly ovoid, 2.8-4 mm, with an obscurely lobed, annular nectary; styles 0.5-3 mm. Capsule ovoid, 7-11 mm. Fl. and fr. Jul-Sep. 2n = 22*, 66, 88, 99, 110.

Alpine scrub, meadows, rock crevices, streamsides, bogs; 3000-5300 m. S Gansu, Qinghai, Shaanxi (Taibai Shan), W Sichuan, NW Yunnan, Xizang [Bhutan, Kashmir, Nepal, Sikkim].

Saxifraga melanocentra, as circumscribed in the present account, is polymorphic. Some of the variation is apparently correlated with chromosome number, while some is possibly associated with putative hybrids with S. pallida. Plants from SW China are smaller and have better-developed nectary discs than their counterparts in Nepal. Preliminary cytological details have been published by Wakabayashi (Newsl. Himalayan Bot. 21: 9-13. 1997).

Two of the present authors (Gornall and Ohba) regard Saxifraga gageana and S. paludosa as distinct species of Micranthes.