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Cassiope mertensiana (Western moss heather)
Cox, Fran

Cassiope mertensiana

Cassiope mertensiana (Bong.) G. Don

Western Moss Heather, Western Moss-heather

Ericaceae (Heath Family)


USDA Symbol: CAME7

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

A low, matted, evergreen shrub with tough branches up to 12 in. tall. Small white bell-like flowers hang from the tips of slender stalks that grow from the axils near the ends of the branches on this matted plant. One to few bell-shaped flowers are borne near the branch tips. Because the flowers are pendent, the reddish sepals are visible.

The somewhat star-like white flowers may have inspired the genus name of this plant, for in Greek mythology Cassiopeia was set among the stars as a constellation. Firemoss Cassiope (C. tetragona), near the Canadian border, has a prominent groove on the lower side of each leaf. Starry Cassiope (C. stellariana), which grows in bogs from Mount Rainier northward, has alternate, spreading leaves.


From the Image Gallery

2 photo(s) available in the Image Gallery

Plant Characteristics

Duration: Perennial
Habit: Subshrub , Shrub
Leaf Retention: Evergreen
Leaf Complexity: Simple
Fruit Type: Capsule
Size Notes: Up to about 1 foot tall.

Bloom Information

Bloom Color: White
Bloom Time: Jun , Jul , Aug , Sep


USA: AK , CA , ID , MT , OR , WA
Canada: AB , BC , YT
Native Distribution: AK to CA, e. to the Canadian Rockies & MT
Native Habitat: Rocky Mt. slopes from timberline upward

Growing Conditions

Light Requirement: Sun
Soil Description: Cool, damp, gritty soil.

Butterflies and Moths of North America (BAMONA)

Cassiope Blue
(Plebejus cassiope)

Larval Host
Learn more at BAMONA

National Wetland Indicator Status

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.


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


Record Modified: 2007-08-19
Research By: TWC Staff

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