Rhododendron tomentosum

It is a low shrub growing to 50 cm (rarely up to 120 cm) tall with evergreen leaves 12–50 mm long and 2–12 mm broad. The flowers are small, with a five-lobed white corolla, and produced several together in a corymb 3–5 cm diameter. They emit strong smell to attract bees and other pollinating insects.

It grows in northern latitudes in North America, Greenland, Canada, and Alaska, in Europe in the northern and central parts, and in Asia south to northern China, Korea and Japan. It grows in peaty soils, shrubby areas, moss and lichen tundra.

All parts of the plant contain poisonous terpenes that affect the central nervous system. First symptoms of overdose are dizziness and disturbances in movement, followed by spasms, nausea, and unconsciousness.^{[citation needed]} Among the plant's terpenes is ledol, a cyclic alcohol with deliriant effects, although poisonous in large doses.^[3][4] No more than a once daily one teaspoonful of dried leaves to one cup of boiling water brewed for 5 min of this beverage should be drunk daily due to ledol and grayanotoxin toxicity.^[5][6]

This species is not to be confused with the traditionally-used one Rhododendron groenlandicum, found throughout Northern North America.