| Marsh Labrador Tea | ||||||||||||||
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 R. tomentosum in flower | ||||||||||||||
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| Rhododendron tomentosum Harmaja | ||||||||||||||
Marsh Labrador Tea, Northern Labrador Tea or Wild Rosemary (Rhododendron tomentosum, formerly Ledum palustre), is a flowering plant in the subsection Ledum of the large genus Rhododendron in the family Ericaceae. 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.
In North America it is found growing in northern latitudes in Greenland, Canada, and Alaska, in Europe south to Germany, and in Asia south to northern China, Korea and Japan. It grows in peaty soils, shrubby areas, moss and lichen tundra.
For its traditional uses in herbal medicine, see Labrador Tea; it has also been traditionally used as a gruit in brewing beer in the Middle Ages. All parts of the plant contain poisonous terpenes that affect central nervous system, causing aggressive behaviour. First symptoms of overdosage are dizziness and disturbances in movement, followed by spasms, nausea and unconsciousness. The mere smell of the plant may cause headache to some people.
