Hedera helix (common name: Common ivy) is a species of ivy native to the most part of Europe and Southwest Asia. It is an evergreen plant that will readily grow up to 20-30 metres if given suitable surfaces to climb on (be it a tree, a wall, a cliff, etc.); otherwise, it will simply grow as a ground cover.
Two forms exist of the plant: the climbing form, and the arborescent form. The former form is considered the juvenile form of the latter; however, Hederas kept as houseplants rarely take the arborescent form.
On level ground they remain creeping, not exceeding 5–20 cm height, but on suitable surfaces for climbing, including trees, natural rock outcrops or man-made structures such as quarry rock faces or built masonry and wooden structures, they can climb to at least 30m above the ground. Hederas have two leaf types, with palmately lobed juvenile leaves on creeping and climbing stems and unlobed cordate adult leaves on fertile flowering stems exposed to full sun, usually high in the crowns of trees or the tops of rock faces, from 2 m or more above ground. The juvenile and adult shoots also differ, the former being slender, flexible and scrambling or climbing with small aerial roots to affix the shoot to the substrate (rock or tree bark), the latter thicker, self-supporting and without roots. The flowers are greenish-yellow with five small petals; they are produced in umbels in autumn to early winter and are very rich in nectar. The fruit is a greenish-black, dark purple or (rarely) yellow berry 5–10 mm diameter with one to five seeds, ripening in late.
Hederas are very popular in cultivation within their native range and compatible climates elsewhere, for their evergreen foliage, attracting wildlife, and for adaptable design uses in narrow planting spaces and on tall or wide walls for aesthetic addition, or to hide unsightly walls, fences and tree stumps. Numerous cultivars with variegated foliage and/or unusual leaf shapes have been selected for horticultural use. Frank Lloyd Wright is attributed with saying “Doctors bury their mistakes, architects cover them with Hedera”