Article from Bean's Trees and Shrubs Hardy in the British Isles
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'Rhamnus infectoria' from the website Trees and Shrubs Online (treesandshrubsonline.
A deciduous shrub of spreading habit up to 7 ft high, the side twigs spine-tipped; young shoots downy. Leaves very variable, mostly oval, but also ovate or obovate; tapered at both ends, finely toothed, 1⁄2 to 11⁄2 in. long, 1⁄4 to 3⁄4 in. wide, upper surface dark green, mostly glabrous, or with down on the midrib, lower one smooth or slightly downy; veins in three or four pairs converging upwards; stalk 1⁄8 to 1⁄3 in. long, usually downy. Fruits two-seeded, black.
Native of S.W. Europe. It has longer, firmer-textured leaves than R. saxatilis, but the two are perhaps only varieties of the one species. The fruit is (or was once) used by dyers under the name of Graine d’Avignon. There is a rather handsome bush at Kew, 7 ft high, and 15 ft in diameter, distinguished by its dense, gnarled branches.