Rhododendron

Rhododendron is a genus of 1,024 species of woody plants in the heath family (Ericaceae), either evergreen or decidary, and found mainly in Asia, although it is also widespread throughout the highlands of the Appalachian Mountains of North America. It is the national flower of Nepal. Most species have brightly colored flowers which bloom from late winter through to early summer.

Description

Rhododendrons are characterized by having clusters of large, bell-shaped flowers with stamens that are longer than the petals. The leaves are spirally arranged; leaf size can range from 1–2 cm (0.4–0.8 in) to over 50 cm (20 in), exceptionally 100 cm (40 in) in R. sinogrande. They may be either evergreen or deciduous. In some species, the undersides of the leaves are covered with scales (lepidote) or hairs (indumentum).

Taxonomy

The Rhododendron genus is the largest of the genera in the Ericaceae family, with 1,024 species, though estimates vary from 850 to 1,000 depending on the authority used. Subgenera include Rhododendron, Hymenanthes, Pentanthera and Therorhodion.

Cultivation

Rhododendrons are extensively hybridized in cultivation, and natural hybrids often occur in areas where species ranges overlap. There are over 28,000 cultivars of Rhododendron in the International Rhododendron Registry held by the Royal Horticultural Society.

Diseases and pests

Rhododendrons can easily be suffocated by other plants or injured by cold. They are susceptible to a number of diseases including Phytophthora root rot and crown rot, honey fungus, and various leaf spot diseases.

See also

• List of Rhododendron species
• Rhododendron maximum
• Rhododendron ponticum
• Rhododendron catawbiense

External links

• American Rhododendron Society
• Danish Rhododendron Society

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