Deciduous Rhododendrons: RHODODENDRON, ro-do-den'dron, a genus of about 600 species of shrubs and trees of the heath family (Ericaceae), native mainly to cooler parts of the Northern Hemisphere. They are most numerous in the Himala}-an region of Asia; some 25 are indigenous to the United States. Many are popular ornamental plants. Rhododendrons may be evergreen or they may lose their leaves in the fall. The deciduous rhododendrons are known as azaleas. (See AZALEA.) Certain rhododendrons, such as Lapland rosebav.
AZALEAS ARE deciduous rhododendrons and their hybrids. The name is also given to a range of compact evergreen shrubs. They are prized for their vibrant colors in late spring and for their fine foliage.
Deciduous azaleas flower in early and mid-summer. They are immensely showy with good-sized flowers in fine clusters and a wonderful color range, including yellow, orange, pink, scarlet, crimson, and many intermediate shades. The flowers of some varieties are very fragrant. In some varieties, the leaves turn copper and crimson before dropping in the fall. Mollis varieties have larger and earlier flowers than the Ghent varieties.
Rhododendrons are propagated by seeds, cuttings, layers, and grafts. They like light shade to full sun and a moist, well-drained soil which is acid and rich in humus. Because of their shallow roots, no cultivation can be given. The plants should be mulched with pine needles, oak leaves, or other organic material. The occasional addition of aluminum sulphate is beneficial if the soil tends to lose its acidity. Rhododendrons have alternate, usually smooth-edged leaves; flowers borne generally in clusters at the ends of branches; a five-parted calyx; five petals that are united below; mostly five or ten stamens; and a five-or ten-chambered, woody, many-seeded capsule.
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