Azalea

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Azalea
Rhododendron 'Hinodegiri'
Rhododendron 'Hinodegiri'
Scientific classification
Kingdom: Plantae
Division: Magnoliophyta
Class: Magnoliopsida
Order: Ericales
Family: Ericaceae
Genus: Rhododendron
Subgenus: Pentanthera
 and
Tsutsusi
Species

see text


Source: The Rhododendron page, and some research.

Azaleas are flowering shrubs making up part of the genus Rhododendron. Originally azaleas were classed as a different genus of plant, but now they are recognised as two of the eight sub-genera of rhododendrons - subgenus Pentanthera (deciduous), and subgenus Titsushi (evergreen).

notes: One major difference between azaleas and the rest of the rhododendron family is their size. Another is their flower growth; rhododendrons grow their flowers in stripers, while most azaleas have terminal blooms (one flower per flower stem). However, they have so many stems that during the flowering season they are a solid mass of colour. Azaleas are recognised by these flowers blooming all at once, in a showy display for a month or two in spring. The exception to this rule is a small group of azaleas which grow their flowers in tight terminal clusters.

Overview

Rhododendron (from the Greek: rhodos, "rose", and dendron, "tree") is a genus of flowering plants in the family Ericaceae. It is a large genus with over 1000 species and most have showy flower displays. It includes the plants known to gardeners as azaleas.

The Rhododendron is an interesting genus characterized by shrubs and small to (rarely) large trees, the smallest species growing to 10-20 cm tall, and the largest, R. arboreum, reported to 50 m tall. The leaves are spirally arranged; leaf size can range from 1-2 cm to over 50 cm, exceptionally 100 cm in R. sinogrande. They may be either evergreen or deciduous. In some species the underside of the leaves are covered with scales (lepidote) or hairs (indumentum). Some of the best known species are noted for their many clusters of large flowers. There are alpine species with small flowers and small leaves, and tropical species such as subgenus Vireya that often grow as epiphytes.

The species are organized by subgenus, section, subsection and series. These are currently divided into four large and four small subgenera:

  • Subgenus Rhododendron L.: small leaf or lepidotes (with scales on the underside of their leaves); several hundred species, type: Rhododendron ferrugineum. The tropical rhododendrons (sect. Vireya, about 300 species) are usually included as a section in this subgenus, but sometimes split off as a ninth subgenus.
  • Subgenus Hymenanthes (Blume) K.Koch: large leaf or elepidotes (without scales on the underside of their leaves); about 140 species, type: Rhododendron degronianum.
  • Subgenus Pentanthera G.Don: deciduous azaleas; about 25 species, type Rhododendron luteum.
  • Subgenus Tsutsusi: evergreen azaleas, about 15 species; type Rhododendron indicum.
  • Subgenus Azaleastrum Planch.: five species; type Rhododendron ovatum.
  • Subgenus Candidastrum (Sleumer) Philipson & Philipson: one species; Rhododendron albiflorum.
  • Subgenus Mumeazalea: one species, Rhododendron semibarbatum.
  • Subgenus Therorhodion: one species, Rhododendron camtschaticum.


Description

One major difference between azaleas and the rest of the rhododendron family is their size. Another is their flower growth; rhododendrons grow their flowers in stripers, while most azaleas have terminal blooms (one flower per flower stem). However, they have so many stems that during the flowering season they are a solid mass of colour. Azaleas are recognised by these flowers blooming all at once, in a showy display for a month or two in spring. The exception to this rule is a small group of azaleas which grow their flowers in tight terminal clusters.

An azalea flower close up

The Satsuki azalea group, derived from Rhododendron indicum and related species, are very popular.

A traditional alcoholic beverage made from azalea blossoms, called dugyeonju (두견주, literally "azalea wine"), is produced in Korea [8].

Cultivation

Plant enthusiasts have created azaleas for hundreds of years. This human genetic modification has produced over 10,000 different cultivars which are propagated by cuttings. Azalea seeds can also be collected and germinated.

File:Azalea1.jpg
Azaleas in bloom

Azaleas grow best in well-drained soil or in plant pots in a cool, shady position. Fertilizer is optional, although some species do need regular pruning.

Several commercial nurseries in Semmes, Alabama, a suburb of Mobile, are major national suppliers of azaleas in the U.S.

Azalea Festivals

Fifty year old Azalea

Many cities in the United States have festivals in the spring celebrating the blooms of the azalea, including Wilmington, North Carolina[1], Norfolk, Virginia[2], Valdosta, Georgia[3] Palatka, Florida[4] Pickens, South Carolina[5] Muskogee, Oklahoma[6] South Gate, California[7] and Mobile, Alabama.

A close up of a red azalea flower

Japan

Motoyama, Kochi also has a flower festival in which the blooming of Tsutsuji is celebrated.


Notes

Credits

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