Vines attach to the bark of trees, brickwork, and other surfaces by way of numerous, small rootlike structures, called haustoria, which exude a gluelike substance. Older vines are known to reach a foot in diameter.
Leaves are dark green, waxy, somewhat leathery, and are arranged alternately along the stem.
Leaves of the mature plant in full sun are often unlobed, oval and have wedge-shaped bases. Fruits mature in Spring and are black with a fleshy outer covering enclosing one to a few hard, stone-like seeds. English ivy is toxic, containing glycosides that cause vomiting, diarrhea, nervous conditions and dermatitis. The fruits of English ivy are toxic to many native songbirds that are attracted to the black berries in Spring when many native fruit sources are limited. English ivy is an aggressive invader that threatens all vegetation levels of forested and open areas, growing along the ground as well as into the forest canopy.