Marsh Labrador Tea

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.

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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.

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.

This species is not to be confused with the traditionally-used one ledum groenlandicum, found essentially in the Labrador region in Canada (where its name comes from).

For traditional uses in herbal medicine, see Labrador Tea (ledum groenlandicum).

Marsh Labrador Tea (ledum palustre) has traditionally been used as a gruit in brewing beer in the Middle Ages. Due to its strong fragrance, it has also formerly been used as a natural anti-moth (for Clothing Moth) in Scandinavia.

External links and references

• Germplasm Resources Information Network: Rhododendron tomentosum
• Flora of China: Ledum palustre
• USDA PLANTS database: Ledum palustre
• Den virtuelle floran: Distribution