Rhododendron macrophyllum D. Don ex G. Don
Pacific Rhododendron, California Rhododendron, California Rosebay, Red Rhododendron
Ericaceae (Heath Family)
Synonym(s): Rhododendron californicum
USDA Symbol: rhma3
California rhododendron is a 5-25 ft. evergreen shrub with large whorls of leathery, dark-green, oblong leaves setting off spectacular flower clusters. Individual flowers are bell-shaped and range in color from pink to deep rose-purple. When growing in woods, the plants become tree-like to 25 ft. with an attractive, leggy appearance. When open-grown the plant is shorter and more compact. Evergreen shrub with large, deep green, leathery leaves and rounded clusters of large, pink, tubular flowers.
This is the showiest flowering shrub in the forests of western North America, with flower clusters that nearly rival in size and number those of its cultivated relatives. Pacific Rhododendron is confined to drier forest environments in western Washington, where it is the state flower. These same environments, however, are among the moister ones occurring in northern California, at the southern limit of this shrub’s range. The plant is most abundant in Oregon, where mass displays provide a spectacular show in late spring and early summer.
From the Image Gallery
Plant CharacteristicsDuration: Perennial
Leaf: Dark Green
Size Class: 12-36 ft.
Bloom InformationBloom Color: Pink , Purple
Bloom Time: Apr , May , Jun , Jul
DistributionUSA: CA , OR , WA
Native Distribution: Coastal B.C. & WA, through the Cascades to n. CA; isolated stations on Vancouver Island
Native Habitat: Coastal, montane conifer woods
Growing ConditionsWater Use: High
Light Requirement: Part Shade , Shade
Soil Moisture: Dry , Moist
Soil pH: Acidic (pH<6.8)
CaCO3 Tolerance: None
Soil Description: Moist to drier, well-drained soil.
Conditions Comments: Not Available
BenefitWarning: Rhododendrons contain poisonous substances and should not be ingested by humans or animals. Honey made from flowers also may be toxic. POISONOUS PARTS: All parts. Highly Toxic, May be Fatal if eaten. Symptoms include salivation, watering of eyes and nose, abdominal pain, loss of energy, depression, nausea and vomiting, diarrhea, weakness, difficult breathing, progressive paralysis of arms and legs, coma. Toxic Principle: Andromedotoxin. (Poisonous Plants of N.C.)
Conspicuous Flowers: yes
Value to Beneficial InsectsSpecial Value to Bumble Bees
This information was provided by the Pollinator Program at The Xerces Society for Invertebrate Conservation.
PropagationDescription: Combine seeds loosely with sphagnum moss and sprinkle lightly over a 2:1 perlite/peat mixture. Optimum temperatures for germination are 45-50 degrees. Transplant seedlings to acid soil with a high content of organic matter. Propagation is also accompli
Seed Treatment: No pretreatment is necessary.
Commercially Avail: yes
Find Seed or Plants
Find seed sources for this species at the Native Seed Network.
National Wetland Indicator Status
From the National Organizations DirectoryAccording to the species list provided by Affiliate Organizations, this plant is on display at the following locations:
Santa Barbara Botanic Garden - Santa Barbara, CA
Native Seed Network - Corvallis, OR
From the ArchiveWildflower Newsletter 1988 VOL. 5, NO.2 - Researching Wildflower Seed Quality, Wildflower Center Receives $500 -000 Gift, ...
Additional resourcesUSDA: Find Rhododendron macrophyllum in USDA Plants
FNA: Find Rhododendron macrophyllum in the Flora of North America (if available)
Google: Search Google for Rhododendron macrophyllum
MetadataRecord Modified: 2010-12-18
Research By: TWC Staff