This section is from the book "Handbook Of Hardy Trees, Shrubs, And Herbaceous Plants", by W. Botting Hemsley. Also available from Amazon: Handbook of hardy trees, shrubs, and herbaceous plants.
Evergreen or deciduous shrubs. Flowers in axillary cymes, often unisexual. Petals sometimes wanting. Disk coating the calyx-tube. Fruit a drupe, with 2 to 4 hard-shelled 1-seeded stones. A genus of sixty species, found in nearly all temperate and tropical countries except Australia. The name is said to be of Celtic origin, signifying a tuft of branches. There are two indigenous deciduous species: one, R. catharticus, a spiny shrub with ovate serrate leaves; and the other, R. Frangula, unarmed, with obovate entire leaves; both have 3-nerved leaves.
1. R. Alaternus. - An evergreen glabrous shrub with linear or ovate-lanceolate serrate shining leaves, very variable in size, and apetalous flowers. There are several varieties, differing in the size, form, and variegation of the foliage. It is a native of the South of Europe. R. latifolius is merely a variety of this.