Rhododendron groenlandicum is accepted species in  the family Ericaceae  subfamily: Ericoideae, tribe: Rhodoreae,  
Genus Rhododendron 
This species is found in Alaska, Alberta, British Columbia, Connecticut, Greenland, Idaho, Labrador, Maine, Manitoba, Massachusetts, Michigan, Minnesota, New Brunswick, New Hampshire, New York, Newfoundland, Northwest Territorie, Nova Scotia, Nunavut, Ontario, Oregon, Pennsylvania, Prince Edward I., Québec, Saskatchewan, Vermont, Washington, Wisconsin, Yukon.