Description from Flora of China
Rubus japonicus Linnaeus, Mant. Pl. 2: 245. 1771; Corchorus japonicus Thunberg.
Shrubs 1–2(–3) m tall. Branchlets green, usually arcuate, terete, angled when young, glabrous. Stipules deciduous after flowering, oblong-lanceolate, membranous, margin ciliate; petiole 5–15 mm, glabrous; leaf blade triangular-ovate or ovate, 3–10 × 2–4 cm, abaxially pilose on veins or in vein axils, adaxially glabrous or sparsely pilose, base subcordate, rounded, or truncate, margin sharply doubly serrate, apex acuminate. Flowers 2.5–6 cm in diam.; pedicel 8–15 mm, glabrous. Sepals persistent in fruit, ovate-elliptic, glabrous, margin serrulate or entire, apex rounded to acute. Petals broadly elliptic, 1.5–2 × 1–1.8 cm, 1–4 × as long as sepals, apex emarginate. Achenes brownish black, obovoid or hemispheric, 4–4.5 × 3.5–4 mm, rugose. Fl. Apr–Jun, fr. Jun–Aug. 2n = 18.
This species is used medicinally and cultivated for ornament.
Thickets on mountain slopes; 200--3000 m. Anhui, Fujian, Gansu, Guizhou, Henan, Hubei, Hunan, Jiangsu, Jiangxi, Shaanxi, Shandong, Sichuan, Yunnan, Zhejiang [Japan].