poison ivy, poison oak, and poison sumac, woody vines and trailing or erect shrubs of the family Anacardiaceae (sumac family), native to North America. They are sometimes considered as several species of Rhus, the sumac genus, but are usually distinguished as Toxicodendron radicans (poison ivy and poison oak) and the larger T. vernix (poison sumac). The whitish berrylike fruits often persist through winter. The leaves of T. radicans are composed of three smooth leaflets. Both species have vivid red autumn foliage. Poison oak is a name generally used in the South and West for the bushy kinds.

The irritant principle, urushiol, is present in almost all parts of the plant. Direct or indirect contact (clothing, tools, or animals that have touched the plant, or smoke from burning the plants) sets off a skin eruption that may vary from simple itching inflammation to watery blisters, depending upon the sensitivity of the individual. The eruption appears within a day to two weeks depending upon sensitivity. It begins on the portion of the body that has come in contact with the plant, usually the hands, which then can spread it to the face and other areas. Washing contaminated skin as soon as possible after contact can reduce the severity of symptoms. These plants are classified in the division Magnoliophyta, class Magnoliopsida, order Sapindales, family Anacardiaceae.

ivy, name applied loosely to any trailing or climbing plant, particularly cultivated forms, but more popularly a designation for Hedera helix, the so-called English ivy, and some related species of the family Araliaceae (ginseng family). Native to Europe and temperate Asia, English ivy is a woody evergreen vine, usually sterile, whose berries contain the poisonous principle hederin. Grown in numerous varieties, it is the most popular house and wall vine. The Boston, or Japanese, ivy (Parthenocissus tricuspidata, of Japan and China) and the American ivy, or Virginia creeper (P. quinquefolia, of North America), are similar species of the family Vitaceae (grape family). Both are sometimes called ampelopsis, a name usually reserved for another related genus. Kenilworth ivy, Cymbalaria muralis, of the family Scrophulariaceae (figwort family) is common to old ruins in Europe; it is often cultivated as a ground cover. Ivy was sacred to Bacchus and was associated with various pagan religions. It was formerly hung as a tavern sign in England. Ivy is classified in the division Magnoliophyta, class Magnoliopsida. The ginseng family ivies are in the order Umbellales, the grape family ivies in the order Rhamnales, and the figwort family ivies in the order Scrophulariales.

ground ivy, trailing perennial herb of the genus Glechoma of the family Labiatae (mint family), closely related to catnip and naturalized from Europe. It forms a dense ground cover and spreads rapidly, thriving in cool, damp places. Its leaves were once used to brew a cough remedy; in quantity it is reputed to be poisonous to horses. Gill-over-the-ground is another of its many names. Ground ivy is classified in the division Magnoliophyta, class Magnoliopsida, order Lamiales, family Labiatae.

Kenilworth ivy, an ivy of the figwort family.

Compton-Burnett, Dame Ivy, 1892-1969, English novelist. Educated at the Univ. of London, she lived quietly in London for most of her life. She was named a Dame Commander of the British Empire in 1967. Ivy Compton-Burnett's unconventional novels of the Edwardian gentry reveal beneath their irony, satire, and wit an embittered, frightful world of hypocrisy and cruelty. Her writings are noted for their lack of plot, their absence of description and characterization, and their almost complete reliance on articulate, highly stylized conversations. Among her most notable works are Brother and Sister (1929), A House and Its Head (1935), Manservant and Maidservant (1947), Mother and Son (1955), The Mighty and Their Fall (1961), and The Last and the First (1971).

Boston ivy or Japanese ivy, tall-climbing woody vine (Parthenocissus tricuspidata) from East Asia, one of the most popular of city wall coverings. Of the same genus as the Virginia creeper and sometimes called ampelopsis, it climbs by disk-tipped tendrils and has three-lobed, or three-parted, leaves, which develop vivid colors in the fall. Boston ivy is classified in the division Magnoliophyta, class Magnoliopsida, order Rhamnales, family Vitaceae.

Either of two North American species of white-fruited woody vines or shrubs of the sumac, or cashew, family. The species found in eastern North America (Toxicodendron radicans) is abundant; a western species, known as poison oak, is less common. Both species are sometimes classified as genus Rhus. A key identifier is leaves with three mitten-shaped leaflets. Contact with urushiol, an oil produced by the plant, can cause severe inflammation and blistering of human skin. Urushiol may be carried from the plant on clothing, shoes, tools, or soil; by animals; or by smoke from burning plants. Because urushiol is nonvolatile, a reaction may result from wearing clothing a year or more after its contact with the plant.

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Any of about five species of evergreen woody vines (rarely shrubs) that make up the genus Hedera in the ginseng family, commonly grown as ground covers and on stone walls, especially English ivy (H. helix), which climbs by aerial roots with adhering disks that develop on the stems. The tough, dark-green leaves of English ivy have three to five lobes and tend to droop horizontally from the stem. Unrelated plants called ivies include Boston ivy (Parthenocissus, or Ampelopsis, tricuspidata), a clinging woody vine in the grape family whose leaves turn bright scarlet in autumn, and poison ivy.

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(born June 5, 1884, Pinner, Middlesex, Eng.—died Aug. 27, 1969, London) British novelist. She graduated from the University of London and published her first novel, Dolores, in 1911. Her second, Pastors and Masters (1925), introduced the style—employing clipped, precise dialogue to reveal her characters and advance the plot—that made her name. Her novels often dealt with struggles for power: Men and Wives (1931) featured a tyrannical mother, A House and Its Head (1935) a tyrannical father. She was created Dame of the British Empire in 1967.

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(born June 5, 1884, Pinner, Middlesex, Eng.—died Aug. 27, 1969, London) British novelist. She graduated from the University of London and published her first novel, Dolores, in 1911. Her second, Pastors and Masters (1925), introduced the style—employing clipped, precise dialogue to reveal her characters and advance the plot—that made her name. Her novels often dealt with struggles for power: Men and Wives (1931) featured a tyrannical mother, A House and Its Head (1935) a tyrannical father. She was created Dame of the British Empire in 1967.

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