Rhododendron occidentale, also known as Western Azalea or California Azalea, is a beautiful deciduous shrub native to Western North America. It is one of two Rhododendron species found in this region, the other being Rhododendron albiflorum. The Western Azalea can be found as far north as Bandon, Oregon, and as far south as the mountains of San Diego County. While typically found in the coastal ranges of Western North America, it can also grow in the Cascade and Sierra Nevada mountain ranges.
This stunning shrub can grow up to 5 meters tall and features deciduous leaves that are 3-9 cm long and 1-3 cm broad. The flowers, which are 3.5-5 cm in diameter, have five lobes on the corolla and vary in color from white to pink, often with a yellow blotch.
One of the unique aspects of the Western Azalea is the considerable diversity in its form and appearance. Genetic diversity seems to be at its highest level along the coast near the Oregon and California border. It is also known for its tolerance of serpentine soils, which can be used as an indicator of its presence in southern Oregon. The Western Azalea is a part of the unique plant community found in the serpentine barrens of the Siskiyou Mountains, along with Darlingtonia californica and Cypripedium californicum. While it is usually found in wetlands, it does not grow with its roots submerged in water. This shrub prefers both more moisture and more sunlight than the evergreen Rhododendron macrophyllum, which has a similar range.
The history of Rhododendron occidentale can be traced back to the nineteenth century when explorers described the plant in western North America. Initially, the different geographic races were classified as separate species. Seed from the Western Azalea was even sent to Veitch Nursery in England in 1850 by William Lobb. This shrub played a significant role in the development of deciduous hybrid azaleas in Great Britain, such as the Exbury azaleas.
Throughout the twentieth century, Rhododendron occidentale has been the subject of ongoing plant exploration by rhododendron enthusiasts. These enthusiasts sought out unusual forms of the Western Azalea for use in gardens and scientific study. Many of these unique forms are now conserved in the Smith-Mossman Western Azalea Garden at Lake Wilderness Arboretum in Maple Valley, Washington state, USA.
The Western Azalea is truly a breathtaking and fragrant addition to any garden. Its fragrant white or slightly pink flowers with a yellow blotch, coupled with its deciduous leaves that turn yellow and scarlet in the fall, make it a standout plant on the Pacific Coast. While it may struggle to thrive on the East Coast, it is well-suited to the unique climate and soil conditions of the Western North American regions it calls home.
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