Rhamnus
(from Rhamnos, the old Greek name used by Theophrastus). Buckthorn. Including Frangula. ORD. Rhamneae. A genus embracing about sixty species of stove, greenhouse, or hardy shrubs or trees, inhabiting temperate and tropical regions. Flowers axillary, racemose or cymose; calyx four or five-cleft, the tube urceolate, the lobes keeled within; petals four or five, cucullate or flat, or wanting; stamens four or five; filaments very short. Drupe berry-like, oblong or spherical, two or four-stoned. Leaves alternate, rarely sub-opposite, petiolate, deciduous or evergreen, penninerved, entire or toothed; stipules small, deciduous. Several of the species afford useful products, especially dyes, and the fruits of many possess violent purgative properties. Few of the plants are valuable from a garden standpoint. The hardy kinds grow in any ordinary soil, and may be propagated by layers, or by seeds. The stove and greenhouse species are easily grown in any light soil, and may be multiplied by cuttings, inserted in sand, under a glass (the stove kinds in heat). Except where otherwise stated, the under-mentioned species are hardy, deciduous shrubs.
R. Alaternus (Alaternus). fl. green, dioecious, disposed in short racemes; petals wanting. April to June. l. ovate-elliptic or lanceolate, coriaceous, quite smooth, serrated. h. 20ft. Mediterranean region, 1629. There are several varieties of this species, the best being one with foliage broadly margined with silvery-white: this is known under the name of R. A. variegata. R. alpinus (alpine). fl. greenish, dioecious, four-parted; female ones with four-cleft stigmas. May and June. fr. black. l. ovallanceolate, crenate-serrated, smooth, lined with many parallel nerves h. 4ft. Europe, &c., 1752. (L. B. C. 1077.) R. californicus (Californian). fl. greenish, pentandrous; panicles on short peduncles. May. l. coriaceous, about 2in. long, elliptic-oblong, entire, revolute on the margins, glabrous; young ones pubescent. h. 6ft. to 12ft. North America, 1874. An unarmed evergreen shrub. SYN. R. oleifolius (H. F. B. A. i. 44).
R. catharticus (cathartic). fl. green, 1/4in. in diameter, fourparted, solitary and fascicled in the axils of the fascicles of leaves on the previous year's wood. May to July. fr. black, 1/4in. in diameter. l. ovate, acutely-serrated, 1in. to 2in. long, fascicled at the ends of the shoots, sub-opposite lower down, shortly petiolate, the young ones downy beneath. h. 5ft. to 10ft. Europe (Britain), &c.(F. D. v. 850; Sy. En. B. 318.) R. croceus (yellow). fl. greenish, in axillary clusters, pentandrous; petals wanting May. fr. greenish or yellowish. l. coriaceous roundish-obovate, about 1/2in. long, lucid; when dry, of a bright yellowish-brown beneath. h. 4ft. California, 1848. A much-branched, thorny, evergreen shrub. (J. H. S. vi., p. 217.) R. davuricus (Dahurian). fl. greenish-yellow, four-parted, numerous, fascicled in the axils. May. l. glabrous, fascicled at the ends of the exceedingly congested branchlets, 3/4in. to 2 1/2in. long, obovate, acuminate, to narrow elliptic-lanceolate. Spines terminating the divaricating branches. h. 15ft. to 20ft. China, Eastern Siberia, &c., 1817. Tree or shrub. SYN. R. utilis. R. d. hirsutus (hairy). l. 2in. long. A large shrub or small tree. R. Frangula (Frangula). Berry-bearing Alder. fl. greenishwhite, five-parted, few, axillary. May and June. fr. black, 1/4in. in diameter, globose, l. obovate, quite entire, alternate; stipules subulate. Branches slender, unarmed. H. 5ft. to 10ft. Europe (Britain), &c. The wood, called Black Dogwood, is used by gunpowder-makers. En. B. 319.) R. latifolius (broad-leaved). fl. greenish, hermaphrodite; calyx villous, four-parted; stigma slightly three-cleft. July. l. elliptic, acuminate, quite entire, lined with twelve or fifteen lateral nerves; younger ones villous. h. 5ft. Azores, 1778. (B. M. 2663; W. D. B. i. 11.) R. libanoticus (Lebanon). fl. yellowish, fasciculate. May. l. clustered at the tips of the branchlets, slightly tomentose, shortly petiolate, ovate or oblong, obtuse, rounded at base, margin finely denticulate. Branches clothed with whitish bark. h. 6ft. Asia Minor and Syria, 1879. Plant unarmed. The foliage turns a dull bronzy-purple in autumn. (B. M. 6721.) R. macrophyllus (large-leaved). fr. black. l. 5in. to 6in. long 2 1/2in. to 3in. broad, coriaceous, dark green and shining above, pale and strongly veined beneath; petioles purplish. China (?), 1876.
R. oleifolius (Olive-leaved). A synonym of R. californicus. R. robustus (strong). fl. green, small. May. fr. black, globose, 1/2in. in diameter. l. broadly ovate-lanceolate, convex, 7in. to 8in. long, 3in. to 3 1/2in. broad, coriaceous, dark green. h. 18ft. 1879. A very vigorous tree. R. utilis (useful). A synonym of R. davuricus.