[7] (The name published by Engelmann was hyphenated, as in viridi-carinatum, but the orthographical variant viridicarinatum is now widely used instead.)

The American botanist Merritt Lyndon Fernald raised the variety to species rank in 1905.

[1] In the United States, it is most common in western Montana, the Great Lakes region, and New England.

[5] In the Pacific Northwest, British Columbia, Montana, and Wyoming, it typically occurs in montane and alpine zones.

[16][17] It is a strict calciphile in Michigan, Pennsylvania, and Vermont,[18][19] but its habitat broadens further north into Canada.