alder buckthorn (EwA Guide to the Plants of the Fells (US))

alder buckthorn

Frangula alnus

Summary ⁴

Frangula alnus, commonly known as the alder buckthorn, glossy buckthorn, or breaking buckthorn, is a tall deciduous shrub in the family Rhamnaceae. It is native to Europe, northernmost Africa, and western Asia, from Ireland and Great Britain north to the 68th parallel in Scandinavia, east to central Siberia and Xinjiang in western China, and south to northern Morocco, Turkey, and the Alborz and Caucasus Mountains; in the northwest of its range (Ireland, Scotland

Description ⁵

Shrubs or small trees, rarely to 7 m tall. Young branches greenish, sparsely puberulent; older branches brownish, with distinct transversely oriented lenticels. Petiole 1-1.9 cm, puberulent, ± glabrescent; leaf blade abaxially pale green, adaxially green, broadly elliptic or oblong, rarely obovate, 4-11 × 2.5-6 cm, papery, abaxially sparsely puberulent on midvein, adaxially glabrous, lateral veins 6-10 pairs, prominent on both surfaces, base broadly cuneate or subrounded, margin entire, apex shortly acuminate or rounded, rarely acute. Flowers solitary or 2-4-fascicled at leaf axils, glabrous. Pedicels 5-10 mm. Sepals keeled and slightly rostrate adaxially. Petals orbicular, apex slightly emarginate. Disk thin, lining calyx tube. Ovary globose, 2- or 3-loculed; style undivided; stigma slightly 2- or 3-lobed. Drupe red, turning purple-black at maturity, 6-8 mm in diam., with 2 or 3 lenticular stones; fruiting pedicel 7-10 mm. Fl. Apr-Jul, fr. Jun-Sep. 2n = 20.