Azalea (Gr. arid), a genus of plants belonging to the natural order ericaceae, and to the sub-order rhodorem, named in allusion to the dry places in which many of the species grow, and consisting of upright shrubs with large, handsome, and fragrant flowers, often cultivated in gardens. The genus comprises more than 100 species, most of them natives of China or North America, having profuse umbelled clusters of white, orange, purple, or variegated flowers, some of which have long been the pride of the gardens of Europe. The general characteristics of the genus are a 5-parted calyx, a 5-lobed, funnel form, slightly irregular corolla, 5 stamens, a 5-celled pod, and alternate, oblong, entire, and ciliated leaves, furnished with a glandular point. The species may be classified into those which have glutinous flowers, and those whose flowers are but slightly or not at all glutinous; each of which classes may be subdivided into those which have short stamens, and those which have stamens much longer than the corolla.

Of those which have a glutinous corolla and short stamens are the viscosa and the glayca, very nearly resembling each other, found native in North America from Maine to Georgia, growing from 4 to 10 feet high, and having many varieties of flowers, either white or tinged with rose color. Of those which have a glutinous corolla, with long stamens, are the nitida, his-pida, and pontioa, the first two being American species and found in mountainous regions in the middle states, the last a native of Turkey and the northern borders of the Black sea, and distinguished by its brilliant yellow corolla. Of those whose flowers are smooth or but slightly glutinous, and have long stamens, are the periclymena, or upright honeysuckle, found on hillsides in all the woods of North America; the canescens, with a white flower which has a red tube, an early and tender American species; and the arborescens, a rare and beautiful shrub, with elegant foliage and very fragrant rose-colored blossoms, found about the Blue Ridge mountains of Pennsylvania. Of those whose flowers are not glutinous, and which have short stamens, are the sinensis, nearly resembling the pontica; the indica, a Chinese species, with brilliant variegated flowers, cultivated in Europe and America as a greenhouse plant; and the ledi-folia, also a native of China, with evergreen leaves, and larger flowers than those of the preceding.

All the American species are deciduous. In cultivation the azaleas love the shade and a soil of sandy peat or loam.

Azalea viscosa.