rhododendron [Gr.,=rose tree], any plant of the genus Rhododendron, shrubs of the family Ericaceae (heath family) found chiefly in mountainous areas of the arctic and north temperate regions and also of the mountainous tropics. Encompassing more than 1,000 species, they are particularly abundant in Asia, whence many of the popular cultivated species and hybrids derive. They commonly have large, shining, leathery, evergreen, semievergreen, or deciduous leaves and clusters of large pink, white, or purplish flowers. Native American species include the great laurel, or rose bay (R. maximum), the common eastern species and the state flower of West Virginia; the mountain rose bay (R. catawbiense) of the southern mountains; and the western rhododendron (R. californicum), the state flower of Washington. The azalea and the rhodora are names used for similar shrubs of the same genus with more typically deciduous leaves. Rhododendrons are classified in the division Magnoliophyta, class Magnoliopsida, order Ericales, family Ericaceae.

Any of about 800 diverse species of woody plants that make up the genus Rhododendron in the heath family, notable for their attractive flowers and handsome foliage. They are native chiefly in the northern temperate zone, especially in South Asia and Malaysia. Some are evergreens, others deciduous. Some are low-growing ground covers; others are tall trees. Flowers are usually tubular to funnel-shaped and occur in a wide range of colours: white, yellow, pink, scarlet, purple, and blue. Seealso azalea.

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