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

Alnus incana subsp. tenuifolia (L.) Moench (Nutt.) Breitung
mountain alder (thinleaf alder)
Betulaceae (Birch family)

Introduction to Vascular Plants

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General:
Deciduous shrub or tree, up to 12 m tall, usually 2-5 m tall, new growth short-hairy; axillary buds with short stalks; bark scaly, often lichen-covered, yellowish-brown or grey.

Leaves:
Alternate, deciduous, smooth, coarsely to irregularly toothed, the teeth pointing outwards, leaf margins not rolled under, brownish in the fall.

Flowers:
Inflorescence of male and female catkins, which open before the leaves on previous year's growth; male catkins with stalks.

Fruits:
Small nutlets, without wings; female cones 1-1.5 cm long, egg-shaped.

Source: The Illustrated Flora of British Columbia

If more than one illustration is available for a species (e.g., separate illustrations were provided for two subspecies) then links to the separate images will be provided below. Note that individual subspecies or varietal illustrations are not always available.

Illustration Source: The Illustrated Flora of British Columbia

Ecological Framework for Alnus incana ssp. tenuifolia

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
Site Information	Avg	Min	Max
Elevation (metres)	1046	393	1693
Slope Gradient (%)	10	0	80
Aspect (degrees) [0 - N; 90 - E; 180 - S; 270 - W]	45	0	360
Soil Moisture Regime (SMR) [0 - very xeric; 4 - mesic; 8 - hydric]	5	1	7
Modal Nutrient Regime Class	D
# of field plots species was recorded in:	161
Modal BEC Zone Class	SBS
All BEC Zones (# of stations/zone) species was recorded in	BG(1), BWBS(6), ESSF(16), ICH(38), IDF(22), MS(27), PP(1), SBS(50)
Source: Klinkenberg 2013

Origin Status	Provincial Status	BC List (Red Blue List)	COSEWIC
Native	S5	Yellow	Not Listed

BC Ministry of Environment: BC Species and Ecosystems Explorer.

Synonyms and Alternate Names:
Alnus purpusii Callier
Alnus purpusii Callier
Alnus incana var. occidentalis subsp. rugosa (Dippel) C.L. Hitchc.
Alnus incana var. occidentalis (Dippel) C.L. Hitchc.
Alnus incana var. virescens S. Wats.
Alnus tenuifolia Nutt.
Alnus tenuifolia var. occidentalis (Nutt.) Breit.

KEY TO ALNUS

1. Leaves finely once or twice saw-toothed; axillary buds unstalked, pointed; male catkins unstalked; stalks as long as or longer than the conelike sillicles..........................A. viridis

1. Leaves coarsely to irregularly round-toothed; axillary buds pedunculate, blunt or short-pointed; male catkins stalked; stalks shorter than the conelike silicles

2. Leaf margins rolled under; nutlets with narrow-winged margins.......................................A. rubra

2. Leaf margins not rolled under; nutlets wingless..................................A. incana

SOURCE: Illustrated Flora of British Columbia, Volume 2

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