HYDRANGEA, a genus of plants of the natural order hydrangeacece, which many botanists make a suborder of distinguished by having 4to 6 petals, 8 to 12 or many stamens, a more or less inferior ovary, and 2 to 5 styles. Ilydrangeacece are shrubs with opposite, or sometimes whorled leaves, destitute of stipules. In the genus hydran gea the flowers are in cymes, the exterior flowers sterile and dilated. Few species are known, and they are chiefly natives of the southern parts of North America, and of China and Japan. The species popularly known as the HYDRANGEA (II. hOrien,Sia), is a native of China and Japan, and has long been in cultivation there as an ornamental plant. It was introduced into Britain by sir Joseph Banks in 1788, and speedily became very popular, being readily propagated by layers and cuttings, so as to be not only a favorite green-house plant, but a frequent ornament of cottage windows. In the s. of England, it endures the open air. It seems almost impossible to water it too freely; a large plant has been known to receive with advantage one hundred gallons of water daily; and in favorable circumstances, it becomes a magnificent shrub. A plant in
Devonshire has had 1,000 large cynics of flowers expanded at once. The flowers, gen erally pink, are sometimes blue; the blue color• is owing to peculiarities of soil. Peat and iron ore are said to be productive of blue flowers in the hydrangea.—IT. tTaponica, introduced into Europe from japan by Siebold, is remarkable for its very large cynics of flowers.—II. nivea and II. querqfolia, American species, are not unfrequently to be seen in flower-gardens iu North America.
or WARNERIA, a genus of plants of the natural order ranunculacece, allied to anemone, but having flowers destitute ofpetals, and succulent or baccate fruit, collected into a head. The only known species, H. canadensis, a perennial herbaceous plant, with tuberous roots, and head of fruit resembling a raspberry, is common in watery places in Canada, and among the Alleghanies, as far s. as Carolina. Its root is used for dyeing yellow, and also in medicine as a tonic. YELLOW ROOT and ORANGE ROOT are its American names.