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

Cassiope mertensiana (Bong.) G. Don
Western Bell Heather (Mertens' moss-heather; Mertens' mountain-heather; western moss heather; white moss-heather; white mountain-heather)
Ericaceae (Crowberry family)

Introduction to Vascular Plants

© Allan Carson  Email the photographer   (Photo ID #17740)

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Distribution of Cassiope mertensiana
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Cassiope mertensiana ssp. mertensiana

Species Information

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Dwarf shrub, mat-forming; stems stiff, ascending, 5-30 cm tall, nearly completely concealed by the leaves, about 4 mm wide including appressed leaves, glabrous or finely hairy.
Evergreen, opposite, distinctly in 4 rows, appressed, egg- to lance-shaped, 2-5 mm long, rounded on the back, grooved only at the extreme base, glabrous or fringed with minutely glandular tiny hairs or longer chaff-like, early deciduous, white hairs; unstalked.
Solitary in leaf axils, usually several near the branch tips, nodding on glabrous or short-hairy stalks 5-30 mm long; corollas white, bell-shaped, 6-8 mm long, the lobes egg-shaped and about 1/3 the length of the tube; calyces reddish, egg-shaped, 2.5-3 mm long, entire to irregular-toothed; stamens not enlarged at the base.
Capsules, nearly globe-shaped, about 4 mm wide.
BC material is var. mertensiana, although some is transitional to the more southern var. gracilis (Piper) C.L. Hitchc.

Source: The Illustrated Flora of British Columbia

Habitat / Range

Mesic to dry slopes, heath, and meadows in the subalpine and alpine zones; common throughout BC, except rare on the Queen Charlotte Islands; N to AK, E to SW AB and MT, and S to CA and NV.

Source: The Illustrated Flora of British Columbia


Ecological Framework for Cassiope mertensiana

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) 10 1794 2649
Slope Gradient (%) 0 27 250
Aspect (degrees)
[0 - N; 90 - E; 180 - S; 270 - W]
0 262 360
Soil Moisture Regime (SMR)
[0 - very xeric; 4 - mesic;
8 - hydric]
0 3 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: AT(69), BAFA(100), cma(69), CWH(25), ESSF(1106), ICH(1), IMA(82), MH(241), MS(1), SBS(3), SWB(37)

Ecological Indicator Information

A very shade-intolerant, subalpine to alpine, Western North American evergreen shrub; distributed more in the Pacific than the Cordilleran region. Occurs in maritime to subcontinental alpine tundra and subalpine boreal climates on moderately dry to fresh, nitrogen-poor soils (Mor humus forms). Plentiful to abundant in heath communities on water-shedding sites; its occurrence decreases with increasing continentality. Associated with Barbilophozia floerkei, Cassiope stelleriana, Phyllodoce empetriformis, and Vaccinium deliciosum. An oxylophytic species characteristic of alpine communities

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 alpine tundra & boreal.

Taxonomic and Nomenclatural Links

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General References