Gen. Hist. 3: 829. 1834,.
Stems spreading or ascending to erect, forming dense mats, puberulent, glandular-hairy, or glabrous. Leaves imbricate, somewhat appressed to leaf above, usually 4-ranked; blade ovatelanceolate, abaxial groove absent, 3–4.5 × 1–1.5 mm, margins thin but not scarious, without curled hairs at leaf tips, surfaces glabrous to glandular-hairy or sparsely hairy. Flowers: sepals 2–3 mm, margins entire or erose; petals connate to 1/3 their lengths, tips recurved, corolla white, campanulate, 5–8 mm; stamens to 3 mm. Capsules 1.5–4 mm.
Alta., B.C., Alaska, Calif., Idaho, Mont., Nev., Oreg., Wash.
Subspecies 4 (4 in the flora).
Four subspecies were recognized by Piper, based on differences in pubescence of the stems and leaf margins.
|1||Stems hairy, especially when young, glandular hairs absent; leaf blade margins glabrous.||Cassiope mertensiana subsp. mertensiana|
|1||Stems glabrous or sparsely glandular-hairy when young; leaf blade margins glandular-hairy, scattered eglandular-hairy, or glabrous||> 2|
|2||Leaf blade margins glabrous||Cassiope mertensiana subsp. gracilis|
|2||Leaf blade margins glandular-hairy or scattered eglandular-hairy||> 3|
|3||Leaf blade margins glandular-hairy; stems glabrous or sometimes sparsely glandular-hairy when young.||Cassiope mertensiana subsp. californica|
|3||Leaf blade margins scattered, branched eglandular-hairy, especially when young; stems glabrous when young.||Cassiope mertensiana subsp. ciliolata|
"/3" is not declared as a valid unit of measurement for this property.