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Rhododendron macrophyllum (Pacific rhododendron) | NPIN
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Rhododendron macrophyllum (Pacific rhododendron)
Bransford, W.D. and Dolphia

Rhododendron macrophyllum

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

USDA Native Status: L48 (N), CAN (N)

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.

 

Plant Characteristics

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

Bloom Information

Bloom Color: Pink , Purple
Bloom Time: Apr , May , Jun , Jul

Distribution

USA: CA , OR , WA
Canada: BC
Native Distribution: Coastal B.C. & WA, through the Cascades to n. CA; isolated stations on Vancouver Island
Native Habitat: Coastal, montane conifer woods

Growing Conditions

Water 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

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

Value to Beneficial Insects

Special Value to Bumble Bees

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

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. 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

Region:AGCPAKAWCBEMPGPHIMWNCNEWMVE
Status: FACU
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 Organizations Directory

According 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 Archive

Wildflower Newsletter 1988 VOL. 5, NO.2 - Researching Wildflower Seed Quality, Wildflower Center Receives $500 -000 Gift, ...

Additional resources

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

Metadata

Record Modified: 2010-12-18
Research By: TWC Staff

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