Ivy
2 of the 6 encyclopedias on this shelf carry an entry for Ivy. Both are reproduced below, so you can see where they agree and where they differ.
Collier's New Encyclopedia (1921)
a climbing plant of the genus Hedera (H. Helix), natural order Araliacex. The leaves are smooth and shining, varying much in form, from oval entire to three and five lobed; and their perpetual verdure gives the plant a beautiful appearance. The flowers are greenish and inconspicuous. H. Helix (the common ivy) is found throughout almost the whole of Europe and in many parts of Asia and Africa. The Irish ivy is cultivated on account of the large size of its foliage and rapid growth. Several varieties of ivy are grown in American gardens. The ivy attains a great age and becomes several inches thick. The wood is soft and porous, and when cut into very thin plates may be used for filtering liquids. In Switzerland and the S. of Europe it is employed in making various useful articles. The ivy has been celebrated from remote antiquity, and was held sacred in some countries, as Greece and Egypt. Its medicinal properties are unimportant. Chinese ivy (Parechites Thunbergii) is a climbing shrub with privet-like leaves and sweet-scented flowers.
Aiton's Encyclopedia (1910)
an ornamental evergreen climbing shrub. It belongs to the same family as ginseng and spikenard, which, however, it does not seem to resemble. Our American ivy or Virginia creeper is not an ivy. Our poison ivy is related to the sumach. The ivy of tradition is a famous climber, holding on to stone walls and trellises by means of numerous rootlets. Authorities claim that ivy drains an old wall of moisture by means of its rootlets and that it preserves woodwork and masonry instead of hastening decay. Ivy adds greatly to the beauty of England. It is preeminently a plant enshrined in sentiment and song. Gray in his Elegy speaks of "yonder ivy-mantled tower." Dickens' most spirited poem is The Ivy: Oh, a dainty plant is the ivy green, That creepeth o'er ruins old! Of right choice food are his meals, I ween, In his cell so lone and cold. Creeping where no life is seen, A rare old plant is the ivy green.
What Has Changed in the Last Century
The botany still holds: ivy is Hedera helix, of the family Araliaceae, and Aiton's 1910 warning that "our American ivy or Virginia creeper is not an ivy" remains good advice. What has reversed is the tone. Collier's 1921 note that "several varieties of ivy are grown in American gardens" now reads as a caution rather than a recommendation, because English ivy has escaped cultivation across the United States and is listed as an invasive or noxious weed in Oregon, Washington and elsewhere, smothering forest floors and climbing native trees. Aiton's confident line that ivy "preserves woodwork and masonry instead of hastening decay" has been partly vindicated by later conservation research, which found the foliage buffers walls against frost and temperature swings while the rootlets can still prise apart mortar that is already cracked. The Irish ivy Collier's mentions is now usually treated as a distinct species, Hedera hibernica.
Written for this edition, 2026.