[www.missouribotanicalgarden.org/] Invasiveness info: Hedera helix, commonly known as English ivy, is a vigorous, aggressive, fast-growing, woody evergreen perennial that is primarily grown as a climbing vine or trailing ground cover. As a climbing vine, it may over time grow upwards to 50-100' in height. As a ground cover, it typically grows to 6-9" tall but spreads over time to 50-100'. English ivy grows in two forms or stages: (1) juvenile stage is the climbing/spreading stage (most often seen) in which plants produces thick, 3-5 lobed, dark green leaves (to 4? long ) on non-flowering stems with adventitious roots, and (2) adult stage is the shrubby non-climbing stage in which lobeless, elliptic-ovate, dark green leaves appear on rootless stems that do not spread or climb, but do produce round, umbrella-like clusters of greenish-white flowers in early fall followed by blue-black berries. Native to Europe, English ivy was brought to the U. S. by settlers in colonial days. It has been and continues to be widely sold in the U. S. as an ornamental plant. It has escaped gardens and naturalized in a large number of eastern, midwestern and pacific coast states. In some climates it is considered highly invasive in woodlands and open areas where it aggressively displaces native vegetation by densely smothering large areas of ground with its trailing densely-leaved stems or by climbing into tree canopies via clinging aerial rootlets. (contributed by Mary Ann Machi)

[Wikipedia] Native to most of Europe and western Asia: Hedera helix, the common ivy, English ivy, European ivy, or just ivy, is a species of flowering plant of the ivy genus in the family Araliaceae, native to most of Europe and western Asia. A rampant, clinging evergreen vine, it is a familiar sight in gardens, waste spaces, and wild areas, where it grows on walls, fences, tree trunks, etc. across its native and introduced habitats. As a result of its hardy nature, and its tendency to grow readily without human assistance, ivy attained popularity as an ornamental plant, but escaped plants have become naturalised outside its native range and grow unchecked in myriad wild and cultivated areas. (contributed by Mary Ann Machi)