Trees, 8-21 m tall; bark grayish, not flaking; branchlets sparsely pubescent or glabrous. Petiole reddish, usually long, (4-)5-15 cm or more, glabrous, base slightly dilated; leaf blade deep green adaxially, broadly ovate, (6-)8-16(-20) × (4-)7-15(-20) cm, thinly leathery, abaxially pruinose, with a small dense patch of hairs at extreme base, elsewhere glabrous, sparsely hairy along veins or pubescent throughout, hairs (except in basal patch) mostly spreading, short, drying whitish or yellowish; adaxially usually glabrous, rarely sparsely hairy along midvein and main veins or throughout, lateral veins ca. 6 pairs, blade usually 5(-7)-veined from base, base cordate, often deeply so, less often rounded, margin serrate, usually coarsely so, apex gradually or more abruptly acuminate. Panicles (13-)20-30 cm; rachis sparsely to more densely pubescent. Flowers unisexual, yellowish green; pedicels 1-1.5 cm, densely pubescent, hairs appressed, yellowish brown, short; bracts lanceolate, 3-10 mm, reducing in size toward apex of rachis, papery, toothed or lobed. Staminate flowers: slightly larger than pistillate ones, 1.2-1.6 cm in diam.; sepals 5-6 × 2-3 mm, ovate to elliptic or slightly obovate, both surfaces densely pubescent, hairs yellowish brown, appressed, short; stamens 5-6 mm; filaments pubescent in lower half, hairs crisped, white when dry; disk glands globose to truncate, small, glabrous. Pistillate flowers: ca. 9 mm in diam.; sepals as in staminate flowers but slightly smaller, 4-5 × ca. 2.5 mm; disk glands globose to truncate, small; ovary superior, globose, glabrous; styles 5 or 6, 0.5-2 mm, joined at base; stigmas 0.5-1 mm in diam. Berry purple-red or orange-red when mature, drying blackish, globose, 8-10 mm in diam., apical scar left by styles pale, circular, flat, small, 0.5-1 mm in diam.; pericarp thin, brittle when dry; stalk 0.6-2 cm. Seeds drying reddish brown or purplish brown, broadly ovoid, 2-3 mm, completely enclosed in a thin, translucent membrane. Fl. Apr-May, fr. Oct-Nov.

Idesia polycarpa is grown as an ornamental.

Deciduous broad-leaved forests, needle-leaved and broad-leaved mixed forests; 400-3000 m. Anhui, Fujian, Guangdong, Guangxi, Guizhou, Hubei, Hunan, Jiangsu, Jiangxi, Shaanxi, Shandong, Sichuan, Yunnan, Taiwan, Zhejiang [Japan, Korea].