Japanese buckthorn Japanese buckthorn

Shrubs or small trees, 1–6 m, armed with thorns. Branchlets reddish brown to gray, glabrous. Leaves deciduous, opposite; petiole 5–16 mm; blade green on both surfaces, obovate to elliptic-oblanceolate or broadly oblanceolate, (2–)3–7 cm, herbaceous, base acute, margins crenate-serrulate, apex acuminate, abaxial surface glabrous or glabrate, adaxial surface minutely hirtellous at least along main veins on distal 1/3, rarely glabrous; secondary veins 4–5 pairs, all diverging at nearly same angle. Inflorescences fascicles or flowers solitary. Pedicels 3–7 mm. Sepals 4. Petals 4. Drupes black, globose, 5–6(–8) mm; stones 2.

Flowering Apr–May. Second-growth woodlands, disturbed sites; 100–300 m; introduced; Ill., Mo.; e Asia (Japan).

Rhamnus japonica was first reported as naturalized in North America from the Morton Arboretum and its immediate vicinity in DuPage County, Illinois (F. Swink and G. Wilhelm 1994).