Rhododendron occidentale

Western Azalea (Rhododendron occidentale )

The Western Azalea (Rhododendron occidentale ) is a shrub or tree of the genus Rhododendron. The white- to rosablütige species is found in western North America. You already came to 1850 in Culture and was crossed in a variety of known rhododendron varieties.

Description

The Western azalea is a deciduous shrub or tree, the plant height can reach up to 8 meters, in extreme cases, up to 10 meters. The bark is smooth or vertically furrowed and fibrous. The branches are densely hairy or irregular or completely bald. The chromosome number is 2n = 26 Like all Rhododendron species also contains the Western Azalea Acetylandromedol which is highly toxic to humans.

Root

The species can thrive in very moist habitats, even in those places where the roots almost in the water. On such wet places the root system is very compact and not by measures more than 1.80 meters in depth and diameter. On drier places the root system is also compact but is supplemented by one or more tap roots that penetrate deeply into the soil.

The leaves sit on glandular or hairy petioles. The leaf blades are ovate, obovate or elliptical, and 3.5 to 8.2 inches long and 1.2 to 2.9 inches wide. They are thin and häutchenartig with ganzrandigem, ciliated or drüsenlos - hairy, rarely with glandular - hairy edge. The blade tip is sharpened or rounded and often mucronate. The midrib is prominent. The Spreitenunterseite is smooth or irregular hairy, often with glandular hairs. The upper leaf surface is dotted with sparse glands loose or glandular trichomes or quite bare.

Flowers

The flower buds are scattered or densely pubescent, ciliate on the edge of the shed or ciliated and glandular. The inflorescence consists of 3-15 flowers. The bracts are similar to bud scales. The pedicels are 9-26 mm long, they are hairy and glandular or rarely non- glandular.

The flowers open with the fan leaves, they stand upright or horizontally. They smell pleasant or extremely unpleasant. The five sepals are fused, the calyx lobes are 1-4 mm long and glandular or non- glandular- hairy.

The funnel-shaped flowers of the Western azalea with respect to the coloring enormously variable. Possible colors of the crown are: white with yellow blotch, white and pink or salmon-colored, pink with orange spot, gradients from white to red on the tube, or more rarely white with yellow stripes. They measure 30-58 mm and are hairy on the inside and outside of glandular or non- glandular, on the outside also bald. The petals are fused and the Corolla lobe measuring 13 to 29 millimeters. The widening tube is 15 to 29 millimeters long, it is the same length or longer than the Corolla lobe. The relatively long Blütentubus means that the Western Azelee can not be pollinated by any insect, but a reliable pollinator is the New World Hyles lineata lined sphinx.

The five stamens are unequal and protrude far from the flower. They have a length between 40 and 75 millimeters.

Fruits

The seed capsules are formed on upright stems and measure 12-22 mm in length and 4-14 mm in width. They are hairy with glandular and non- glandular. The seeds are not clearly winged. The seed coat is thickened at the two ends of the flattened seeds.

Distribution and location

The natural range is in California and Oregon, as well as in the far north of Baja California. They settled there, the Cascade Range, the Klamath Mountains and the California Coast Ranges. In California, the Western Azalea in the Sierra Nevada and the Peninsular Ranges is widespread. Smaller deposits are found on the bay of San Francisco. The northernmost occurrence is Bandon (Oregon ), the southernmost on Palomar Mountain in Mexico.

The Western azalea thrives in moist, wooded slopes and at the base of the canyon, river banks, on ridges and in thickets, and in swamps on the Pacific coastal cliffs at altitudes 0-2700 meters. It likes to grow in communion with the cobra lily ( Darlingtonia californica ) and the California Lady's Slipper ( Cypripedium californicum ). Even with Lilium pardalinum subsp. pitkinense lives socialized the way.

System

Within the genus Rhododendron is the kind subsection Pentanthera containing a total of 14 species found in the section Pentanthera.

An investigation of the flavonoids in the leaf of 18 North American Rhododendron species from 1977 revealed that the closest relatives of the Western Azalea Rhododendron austrinum and the Pontic azalea are (Rhododendron luteum ). A broader molecular genetic analysis of the RNA polymerase RPB1 from 2005 took into account a total of 87 rhododendron species. One result was that the section Pentanthera is paraphyletic. As a next of kin of the Western Azalea Rhododendron canescens was found. Also in this work, there was a close relationship to the Pontic azalea (Rhododendron luteum ). Rhododendron austrinum was not among the species studied. Another paper from the year 2000, which examines the relationship within the section Pentanthera based on ITS sequences, confirms once again the close relationship to Rhododendron luteum.

The species is divided into three varieties:

• Rhododendron occidentale var occidentale, the Nominotypisches taxon
• Rhododendron occidentale var paludosum
• Rhododendron occidentale var sonomense

Culture

The Western Azalea was discovered by Frederick William Beechey in 1827 and then collected by David Douglas, Karl Theodor Hartweg and Joseph Burke II. William Lobb sent in 1850, the first seeds to England at the Veitch Nurseries, where it bloomed for the first time in 1857. First hybrids were drawn by Anthony Waterer in the 1870 ern.

M. Koster & Sons crossed already in 1895 the Western Azalea with hybrids of the Japanese azalea (Rhododendron molle ).

The first monograph on the nature was written in the 1950s by Leonard Frisbie and published in 1961.

Significant hybrids are:

• ' Delicatissimum ' - ( Koster ) with creamy white and pink uncrowded flowers with a yellow spot, the smell.
• ' Exquisitum ' - ( Koster, 1901) with an orange-yellow spot, the strongly scented with ruffled, weißlichrosanen flowers.
• ' Irene Koster ' - ( Koster ) late flowering variety with pink flowers with a small stain.
• ' Magnificum ' - ( Koster, 1910) with purple -red flowers and a golden stain.
• ' Summer Fragrance ' - ( R. occidentale × luteum, Pratt, 1963) pale yellow with a strong yellow stain.

They were all awarded in 1993 with the RHS Award of Garden Merit.