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Rhododendron occidentale (Western azalea)
Sherman, Doug

Rhododendron occidentale

Rhododendron occidentale (Torr. & A. Gray) A. Gray

Western azalea

Ericaceae (Heath Family)

Synonym(s):

USDA Symbol: rhoc

USDA Native Status: L48 (N)

A fragrant, loosely branched, spreading shrub that can reach 15 ft. in height but is usually 3-9 ft. tall. The bark is shredding. The leaves are thin, light green and oval. White, tubular flowers may be tinged pink and have a yellow-blotched upper lobe. Flowers occur in tightly compact clusters. A shrub with large, white to deep pink, very fragrant flowers in large clusters at stem ends.

Flower variations include mixtures of pale pink, deep pink, and yellow-orange. An evergreen, pink-flowered relative, California Rosebay (R. macrophyllum), grows from British Columbia to California and makes a choice ornamental; it is the state flower of Washington, where it is known as Red Rhododendron.

 

Plant Characteristics

Duration: Perennial
Habit: Shrub
Leaf: Green
Flower:
Fruit:
Size Class: 12-36 ft.

Bloom Information

Bloom Color: White
Bloom Time: Apr , May , Jun , Jul , Aug

Distribution

USA: CA , OR
Native Distribution: CA mts. from Kern & Santa Cruz Cos., n. to s.w. OR
Native Habitat: Stream banks and other moist places below 7500 ft.

Growing Conditions

Water Use: High
Light Requirement: Part Shade
Soil Moisture: Moist
Soil pH: Acidic (pH<6.8)
CaCO3 Tolerance: None
Soil Description: Moist, well-drained soil.
Conditions Comments: A parent of many hybrid azaleas.

Benefit

Warning: 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

Propagation

Description: 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. Cultivated evergreen azaleas
Seed Treatment: No pretreatment is necessary.
Commercially Avail: yes

Value to Beneficial Insects

Special Value to Bumble Bees

This information was provided by the Pollinator Program at The Xerces Society for Invertebrate Conservation.

Butterflies and Moths of North America (BAMONA)

Rhododendron occidentale is a larval host and/or nectar source for:
Hoary Comma
(Polygonia gracilis)

Food Source
Learn more at BAMONA

National Wetland Indicator Status

Region:AGCPAKAWCBEMPGPHIMWNCNEWMVE
Status: FAC FAC
This information is derived from the U.S. Army Corps of Engineers National Wetland Plant List, Version 3.1 (Lichvar, R.W. 2013. The National Wetland Plant List: 2013 wetland ratings. Phytoneuron 2013-49: 1-241). Click here for map of regions.

From the National Suppliers Directory

According to the inventory provided by Associate Suppliers, this plant is available at the following locations:

Oregon Native Plant Nursery - Woodburn, OR

From the National Organizations Directory

According to the species list provided by Affiliate Organizations, this plant is either on display or available from the following:

Santa Barbara Botanic Garden - Santa Barbara, CA

Bibliography

Bibref 1186 - Field Guide to Moths of Eastern North America (2005) Covell, C.V., Jr.
Bibref 1185 - Field Guide to Western Butterflies (Peterson Field Guides) (1999) Opler, P.A. and A.B. Wright

Search More Titles in Bibliography

Additional resources

USDA: Find Rhododendron occidentale in USDA Plants
FNA: Find Rhododendron occidentale in the Flora of North America (if available)
Google: Search Google for Rhododendron occidentale

Metadata

Record Last Modified: 2010-11-23
Research By: TWC Staff

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