Description from Flora of China
Rhamnus davurica Pallas var. liukiuensis E. H. Wilson, J. Arnold Arbor. 1: 181. 1920.
Shrubs dioecious, to 4 m tall, unarmed. Young branches glabrous, alternate, purplish to grayish brown, without spines. Leaves alternate or fascicled on short shoots; stipules linear, 3-5 mm; petiole 8-15(-20) mm, adaxially canaliculate, sparsely puberulent; leaf blade pale green abaxially, deep green adaxially, ovate or broadly elliptic-ovate, 4-8(-10) × 3-6 cm, membranous or thinly papery, abaxially sparsely pilose on major veins or in vein axils, adaxially glabrous, lateral veins 4 or 5 pairs, prominent abaxially, impressed adaxially, base obtuse to acute, margin serrate, apex acute or acuminate. Flowers unisexual, glabrous, usually fascicled on short shoots or in leaf axils of lower parts of branches. Calyx tube campanulate; sepals triangular-lanceolate, apex acute. Petals much shorter than sepals, lanceolate, caducous. Stamens equaling petals. Ovary slightly inferior, 2- or 3-loculed; style 2- or 3-branched. Drupe reddish when mature, globose, 2- or 3-grooved longitudinally, glabrous, with 2 or 3 stones, with persistent calyx tube at base; fruiting pedicel 6-7 mm, glabrous. Seeds unknown. Fl. Feb-Mar, fr. Jun-Aug.
Sparse forests; high elevations. C Taiwan [Japan (including Ryukyu Islands)].