60. Spiraea thunbergii Siebold ex Blume, Bijdr. Fl. Ned. Ind. 17: 1115. 1826.
珍珠绣线菊 zhen zhu xiu xian ju
Shrubs to 1.5 m. Branches spreading, arching, slender; branchlets brown to red-brown, angled, pubescent at fist, finally glabrous; buds ovoid, very small, with several scales, glabrous or puberulous. Petiole 1–2 mm, pubescent; leaf blade linear-lanceolate, 25–40 × 3–7 mm, glabrous on both surfaces, pinnately veined, base narrowly cuneate, margin sharply serrate above middle, apex long acuminate. Umbels sessile, with clustered leaves at base, 10–18 mm, 3–7-flowered; pedicels slender, 6–10 mm, glabrous. Flowers 6–8 mm in diam. Hypanthium campanulate, glabrous abaxially. Sepals triangular or ovate-triangular, 1.5–2 × 1–1.5 mm, erect or reflexed in fruit, apex acute. Petals white, obovate to suborbicular, 2–4 × 2–3.5 mm, glabrous, base shortly clawed, apex emarginate or obtuse. Stamens 18–20, to 1/3 as long as petals. Disk annular, 10-lobed. Carpels glabrous or puberulous; styles nearly equaling stamens. Follicles spreading, glabrous; styles subterminal, divergent. Fl. Apr–May, fr. Jul–Aug.
Native in E China; cultivated for ornament in Fujian, Jiangsu, Liaoning, Shaanxi, Shandong, Zhejiang, and other provinces [Japan].