hydrangea

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. Any of various shrubs of the genus Hydrangea, having opposite leaves and large, flat-topped or rounded clusters of white, pink, or blue flowers.

Century Dictionary and Cyclopedia

1. n. A genus of shrubs or herbs, of the natural order Saxifrageæ, type of tribe Hydrangeæ, containing about 33 species, natives of Asia and America, characterized by having the ovary inferior, 4 or 5 valvate petals, 4 or 5 styles, free or connate at base, the fruit a capsule, and the leaves deciduous or persistent. The common hydrangea, H. Hortensia, is a native of China. It was introduced into England by Sir J. Banks in 1790. It is a favorite for the beauty and size of its flowers, which form immense globular clusters, blue, pink, or white. H. arborescens, the wild American hydrangea, was introduced into European cultivation from Virginia in 1736; it is not much cultivated in the United States. H. quercifolia, the oak-leafed hydrangea, is wild from Georgia south, and is hardy at the north in cultivation. The genus is found in a fossil state, five extinct species having been described from the Miocene of Europe. Sometimes spelled Hydrangia.
2. n. [lowercase] A plant of this genus.

Wiktionary

1. n. Any of several shrubs, of the genus Hydrangea, having large clusters of white, pink or blue flowers

GNU Webster's 1913

1. (Bot.) A genus of shrubby plants bearing opposite leaves and large heads of showy flowers, white, or of various colors. Hydrangea hortensis, the common garden species, is a native of China or Japan.

WordNet 3.0

1. n. any of various deciduous or evergreen shrubs of the genus Hydrangea