Rhododendron 'Chlorinda'. Photo by Marc Johnson.
The home of Vireya Rhododendrons lies in the steamy, moist cloud forests of Malaysia and Indochina, and on the islands of Indonesia, New Guinea and the Philippines. With their brilliant trusses of flowers, some tubular, some flaring, in yellows, orange, shades of reds, even bi-colors, they hang as epiphytes from trees, in clefts of rocks, in sunny openings in the jungles, even at elevations of 10,000 feet! They produce quantities of seeds, and through the help of wind or birds find a variety of homes in these humid tropics as long as there is moisture, a frost-free climate, acid soil, and good drainage. Adjacent to the Succulent Garden, the Southeast Asian Cloud Forest is a new section of the San Francisco Botanical Garden now providing habitat for this group of rhododendrons.
Vireya is a subgenus of the genus Rhododendron, distinguished primarily by their seeds which have tails at both ends. Their flamboyant colored and shaped flowers also tend toward multiple bloomings throughout the year. Approximately 900 species of Rhododendron exist in the world and one third of them are Vireyas!
In the 19th century, the great nursery Veitch & Sons in Exeter, England sent their own explorers to China and the Himalayas – even to southern Appalachia and California – to bring back varieties of rhododendron for hybridizing in English greenhouses. The Depression and two World Wars took their toll, and interest waned until 1958-1960 when Dutch botanist Professor Hermann Sleumer travelled to New Guinea and discovered 122 new species. He wrote the first classification of Vireyas still used today. The San Francisco Botranical Garden was one of four botanical gardens along with Kew Gardens chosen to receive his cuttings. In 2002, SFBG Collections manager Bian Tan brought back seeds and cuttings from Indonesia. Some did not survive several rare severe California frosts, however, planting cuttings from other growers have been successful and made up for the losses. Many beautiful hybrid crosses and cultivars have arisen in the Vireya trade.
Morning sun is best, so Vireyas in the Southeast Asian Cloud Forest are planted in the dappled shade of Magnolias, Fishtail Palms, Cinnnamomum (Camphor trees), and under Podocarpus and red leafed Elaeocarpus from Taiwan. Growing with them are clumps of Vaccinium sp. (blueberries from Burma), Dichroa sp. (Hydrangeas from Indochina), and Gaultheria sp., a plant we know well that grows in our own dank coastal forests. San Francisco fog supplies most of the moisture, and the Bay provides the mild temperatures they need. We have 15 varieties of Vireya that go in and out of bloom in spring, among them, creamy white R. 'Elizabeth Ann Seton' and rosy R. hellwigii.
||Rhododendron spp., In Section Vireya of Subgenus Rhododendron
||Shrubby epiphytes or terrestrial shrubs
||Prefers cool shade, regular watering, good drainage, acidic soil and a frost-free climate
||Spring, but many bloom sporadically through the seasons
||Accent plants in shady gardens.
||Rhododendrons of Subgenus Vireya Hardcover – May, 2006 by George Dr. Argent, available at Helen Crocker Russell Library of Horticulture
Some Vireya Rhododendrons of the SACF include: Rhododendron 'Elizabeth Ann Seton', R. 'Chlorinda', R. 'Doris Mossman', R. gracilentum x lochiae x laetum, R. hellwigii x konori, R. x (konori x laetum) x zoelleri, R. laetum, R. x (laetum x lowii)
R. quadrasianum, R. rarum, R. 'Ravalac', R. 'Red Rocks', R. 'Souvenir De J.H. Mangles', R. 'Taylori'
IN BLOOM CONTRIBUTORS:
Text by Kathy McNeil. Profile by Mona Bourell. Photos by Joanne Taylor, Mona Bourell and Marc Johnson.