石灰岩绣线菊 shi hui yan xiu xian ju

Shrubs low, to 1.5 m tall. Branches spreading, arching; branchlets purple-brown, turning gray-brown to gray-black when old, distinctly angled; buds ovoid, small, with several scales, glabrous or puberulous on scale margin, apex subobtuse or acute. Leaves fascicled on short branchlets, alternate on long branchlets; petiole very short or absent, glabrous; leaf blade obovate, rarely elliptic, 5–9 × 2–6 mm, glabrous on both surfaces, base cuneate and 3-veined, margin entire, apex obtuse. Umbels sessile, 8–12 mm, 6–10-flowered, with small, clustered leaves at base; pedicels 3–7 mm, glabrous; bracts linear-lanceolate, glabrous, caducous. Flowers 4–6 mm in diam. Hypanthium campanulate, glabrous abaxially. Sepals triangular, 1–1.5 × 1.5 mm, erect in fruit, apex acute. Petals pinkish, obovate, 2–3 × 2–2.5 mm, glabrous, base shortly clawed, apex emarginate or obtuse. Stamens ca. 20, slightly shorter than to subequaling petals; disk undulate annular. Carpels puberulous; styles shorter than stamens. Follicles spreading, glabrous; styles terminal on abaxial side, somewhat divergent.

Limestone mountain slopes; 2700--2800 m. NW Yunnan.

Spiraea thibetica Bureau & Franchet (J. Bot. (Morot) 5: 25. 1891, not S. tibetica T. T. Yü & L. T. Lu, 1980), described from Xizang, requires further study. We are unable to treat it in this account because we have seen no specimens.