Hedera helix L.
English ivy is native to most of Europe. Introduced to North America and Australia, it is now considered an invasive in some areas.
Identification: English ivy is a climbing vine that reaches 66-98' (20-30 m) in height, clinging to rocks, trees and buildings with sticky aerial rootlets, and spreading to cover the substrate almost completely. Vines in well-established plants can reach up to 12" (30 cm) in diameter. Younger leaves have five (rarely three) pointed lobes; in older leaves, the lobes become less divided. Leaves are dark green and waxy or shiny, with prominent, light-colored veins, 1½-4" (3.8-10 cm) long. It takes many years for a vine to begin flowering, and the flowers are inconspicuous, small and greenish. Berries are purple or black, about ¼" (6.3 mm) in diameter, and also rare.
English ivy is considered an invasive in some areas because it climbs over and kills many other plants, establishing a less healthy monoculture in place of a more diverse plant community.
Hedera helix on Carolina Nature, from Will Cook
Hedera helix on Forest and Kim Starr’s Starr Environmental site
Hedera helix on Wikipedia
Hedera helix at the University of Connecticut Plant Database
Hedera helix on the Plant Conservation Alliance’s Alien Plant Working Group Least Wanted List
Hedera helix on Plants for a Future, a resource and information centre for edible and otherwise useful plants
Hedera helix on FLORIDATA
Hedera helix on the USDA Forest Service's Fire Effects Information Database
Hedera helix description by Thomas H. Kent, last updated 16 Aug 2013.