Ivy

Ivy, a genus of evergreen climbing shrubs with scattered simple exstipulate leaves, a simply umbellate inflorescence of symmetrically pentamerous flowers, and a, globular five-chambered baccate fruit. They have an epigynous disk and a slightly ruminated albumen. The genus, known botanically as Hedera, is the type of the order Hederacene, and the numerous recorded species, native to the Old World, may be reduced to three. H. helix, the common ivy of Europe, is a variable plant. It climbs on rocks, trees, or walls by means of numerous adventitious rootlets or claspers (French crampons), and its stems, which have a thick cork, may reach 10 inches in diameter. The leaves on the climbing part of the plant are three- to five-lobed, and it is not until it reaches the top of a tree or wall that the plant bears any flowers. Before doing so it branches horizontally and bears ovate unlobed leaves. The flowers are greenish, and on their stalks and calices have stellate hairs. The berries are black or rarely yellow. The plant is in no sense a parasite, but has an injurious mechanically constrictive action on tree-stems. On sound walls it promotes dryness or warmth; but if its shoots penetrate between stones or bricks its growth will overthrow the building.