48. Arenaria nigricans Handel-Mazzetti, Symb. Sin. 7: 196. 1929.
变黑无心菜 bian hei wu xin cai
Herbs. Root solitary, small; rootlets white, long, fibrous. Stems branched at base, 10--25 cm, black glandular hairy. Basal leaves petiolate; leaf blade suborbicular. Cauline leaves with sheathing petiole; leaf blade narrowly elliptic to suborbicular, 1--4 × 0.7--1.5 cm, thick, bullate, both surfaces glabrous, base attenuate, margin ciliate, apex obtuse. Cymes many flowered; bracts ovate or broadly so, 5--8 mm, apex acute. Pedicel erect in fruit, 1--4 cm, becoming shorter distally on cymes, glandular villous. Sepals 5, orbicular, 4--5 mm, glandular pubescent abaxially, base narrowed, margin membranous, apex rounded. Petals 5, white, obovate, 1--2 × as long as sepals, apex truncate or emarginate. Floral disc small, with 5 subglobose glands. Stamens 10, equaling sepals; anthers yellow. Ovary turbinate-obovoid, ca. 1/3 as long as sepals. Styles 2, equaling ovary. Capsule 4-valved. Seeds brown, large, smooth, narrowly fimbriate. Fl. Jul--Sep.
* Limestone and montane rock crevices; 2600--3500 m. W Yunnan.
Two varieties have been recognized. The distinguishing characters seem to be only a matter of degree or ecologically induced, and the variation pattern should be studied in the field. Perhaps this variation should not be the basis for formal recognition of taxa.