Introduction to Rhododendrons
The word rhododendron comes from the Greek words "rhodon", or rose, and "dendron", or tree. They offer an almost limitless range of size, shape, texture, growth habit, and color of blossoms and foliage. From a miniature a few inches high to a giant of 60 to 80 feet in their native Southeast Asia, rhododendrons can grow straight up, gnarled and twisted, wide and spreading, rounded, and even ground-hugging. The flowers are of various shapes and sizes, usually in a rounded cluster or truss that can be gigantic. Rhododendrons come in a wondrously large selection of colors covering the full range of the rainbow except for true blue. There is a palette of mixes of colors, shadings and tints as well as one color tinged with another.
Even when not in bloom, the subtle beauty of the rhododendron foliage is a joy to those who appreciate them. The simple play of light and shadow brings out the texture and shape of leaves which can be smooth or rough, glossy or matte, many shades of green or overshaded with beautiful fall colors of bronze and brown. Leaves range in size from 1/8 inch to 2.5 feet long!
Fossil records show that rhododendrons grew in Europe and North America fifty million years ago. Rhododendrons were first recommended for garden use in 1629, but the botanical name of the genus was not clearly established until 1753 when Linnaeus recorded the genus Rhododendron in Species Plantarum. California native rhododendrons became known in 1792, and received the species name Rhododendron macrophyllum. By 1800 there were only twelve species known in cultivation.
The first of the vast flood of rhododendrons from Southeast Asia was the magnificent tree species, Rhododendron arboreum, which arrived from India in 1811. Several magnificent examples of this species grace the Mendocino Coast Botanical Gardens. In the 1860's and 70's the United States received a few rhododendrons from Europe for landscaping the Capitol building in Washington D.C. In 1887 seven varieties were planted in Golden Gate Park, and probably about that number existed in the whole of Western America. The Park director, John McLaren, wanted mass plantings and imported new species and hybrids as they became available. By 1893, 44 rhododendron varieties were growing in Golden Gate Park, and by 1910 the list had grown to 85. Plant hunters and missionaries continued sending seed home and soon there were about 300 species known to botanists.
There are over ten thousand named hybrids in the world, with many more introduced each year. Species continue to be found and introduced as their native areas become open to researchers. To date, over eight hundred species have been identified and named.