E-Flora BC: Electronic Atlas of the Flora of British Columbia

Alnus rubra Bong.
red alder
Betulaceae (Birch family)

Introduction to Vascular Plants

© Brian Klinkenberg  Email the photographer   (Photo ID #3768)

E-Flora BC Static Map
Distribution of Alnus rubra
Click here to view our interactive map and legend
Details about map content are available here
Click on the map dots to view record details.

Species Information

Click on the image below to view an expanded illustration for this species.

Deciduous shrub or tree, up to 25 m tall; axillary buds with stalks; bark scaly, often lichen-covered, yellowish-brown or grey-splotched with white.
Alternate, deciduous, smooth, coarsely to irregularly toothed, the teeth pointing outwards, leaf margins rolled under, brownish in the fall.
Inflorescence of male and female catkins which open before the leaves enlarge; male catkins with stalks.
Small nutlets, with narrow-winged margins; female cones 1.5-2.5 cm long, egg-shaped.

Source: The Illustrated Flora of British Columbia

USDA Species Characteristics

Flower Colour:
Blooming Period:
Early Spring
Fruit/Seed characteristics:
Colour: Brown
Present from Fall to Spring
Source:  The USDA

Habitat / Range

Moist woodlands, forests, floodplains and clearcuts in the lowland and montane zones; common in coastal BC; N to SE AK and S to CA.

Source: The Illustrated Flora of British Columbia

Additional Notes

Cut-leaf Red Alder

Red alder is probably the most common deciduous tree in the southern part of British Columbia. The leaves normally have shallow, rounded teeth along their margins. The leaves of the cut-leaf mutant form have irregular, sharply pointed teeth and lobes, thus resembling some black oak leaves more than alder leaves.

Source: Extracted with permission from Griffiths and Ganders, 1983.

Flowering Period

This species flowers in the first week in March in the Fraser Delta.


Ecological Framework for Alnus rubra

The table below shows the species-specific information calculated from
original data (BEC database) provided by the BC Ministry of Forests and Range.
(Updated August, 2013)

Site Information
Value / Class




Elevation (metres) 0 128 1700
Slope Gradient (%) 0 12 150
Aspect (degrees)
[0 - N; 90 - E; 180 - S; 270 - W]
0 167 360
Soil Moisture Regime (SMR)
[0 - very xeric; 4 - mesic;
8 - hydric]
0 5 8
Modal Nutrient Regime
Number of field plots
 species was recorded in:
Modal BEC Zone Class
All BEC Zones (# of stations/zone) species was recorded in: BWBS(1), CDF(151), CWH(1265), ICH(9), IDF(7), MH(4), SBS(1), SWB(1)

Ecological Indicator Information

A shade-intolerant, sub montane to montane, Pacific North American deciduous broad­leaved tree. An abundant species that grows in cool mesothermal climates on nitrogen-rich soils (Moder and Mull humus forms); its occurrence decreases with increasing elevation and continentality. Forms dense stands in the initial stages of primary succession on floodplains or secondary succession on water­shedding sites. Persists along streams and on water-collecting sites, usually associated with Lysichitum americanum; tolerates fluctuating groundwater tables. This fast -growing tree regenerates abundantly from seed on exposed mineral soil and from stump sprouts following cutting. May hinder regeneration and growth of conifers. Symbiosis with nitrogen­fixing Actinomycetes enhances the supply of available soil nitrogen. Suitable as a temporary nurse species for shade-tolerant conifers, especially on nitrogen-deficient sites; however, it may decrease both soil pH and base content of some soils. Characteristic of young­seral mesothermal forests.

SourceIndicator Plants of Coastal British Columbia (Information applies to coastal locations only)


The climate type for this species, as reported in the: "British Columbia plant species codes and selected attributes. Version 6 Database" (Meidinger et al. 2008), is cool mesothermal.

Synonyms and Alternate Names

Alnus oregona Nutt.
Alnus oregona var. pinnatisecta Starker

Taxonomic and Nomenclatural Links

Additional Photo Sources

Species References

Griffiths, Anthony J. F. and Fred R. Ganders. 1983. Wildflower Genetics: A Field Guide for British Columbia and the Pacific Northwest. Flight Press, Vancouver.

General References