Labrador Tea – Rhododendron tomentosum

Alaska Wildflowers | White

Labrador tea

Rhododendron tomentosum Harmaja

Alt. Names:
Ledum palustre L.
Wild rosemary
Northern Labrador tea
Marsh Labrador tea
Bog Labrador tea

Genus: Rhododendron
Family: Ericaceae
Order: Ericales

Duration: Perennial

Similar species:
Rhododendron groenlandicum, previously known as Ledum groenlandicum, and Rhododendron neoglandulosum, previously known as Ledum glandulosum also go by the common name “Labrador tea.” Rhododendron groenlandicum is nearly identical to Rhododendron tomentosum, the main difference being the germination rate, the fungi, or “rust parasite” living on the underside of the leaves, and the plants’ distribution (Rhododendron groenlandicum is not native to Europe or Asia). Rhododendron neoglandulosum has wider leaves, but is not native to Alaska (confined to western US and Canada).

Uses: Tea can be made from the leaves, but with caution (small concentrations). During the Middle Ages, Labrador Tea was used in brewing beer to make it more intoxicating and give it more of a head. The entire plant contains ledol, a poisonous terpene that can cause dizziness, nausea, unconsciousness, cramps, and paralysis. Historically, Labrador tea has been used to treat muscle pain, diarrhea, and chest congestion, but potential side effects most likely outweigh any benefits. Paul Kirtley has a great blog post explaining more on potential uses/hazards.

Identification – Labrador tea

Rhododendron tomentosum is a low to medium-sized evergreen shrub. The leaves are green, long (12-50mm/0.5-2 inches), and oblong, leathery, and look like large rosemary leaves. The leaves are alternate on a woody stem. The underside of the leaves is a rusty brown. Usually, each plant has several white-flowered inflorescences. The individual flowers are small, about 1 cm in diameter. Each flower typically 5-petaled with 10 long stamens. Labrador tea leaves and flowers are both fragrant.

Range and Habitat

Rhododendron tomentosum is native to Alaska, Canada, Greenland, northern and central Europe, northern China, Korea, and Japan. It grows in bogs, woods with peaty soils, alpine slopes, and tundra. Because it lives well in acidic soils with poor nutrient supply, it is often found in black spruce forests in the interior of Alaska. Rhododendron groenlandicum has a similar range and habitat but is not found in Eurasia.

References and More Reading

Field Guide to Alaskan Wildflowers, Pratt, Verna E. pg 60
Rhododendron tomentosum  Harmaja, ITIS Database
Labrador Tea: Tonic or Toxic, Paul Kirtley’s Blog
BOG LABRADOR TEA, WebMD: Vitamins & Supplements
Labrador Tea, Ledum groenlandicum, Edible Wild Food
Flora of the Canadian Arctic Archipelago, S.G. Aiken Et al.
Plant Guide BOG LABRADOR TEA, USDA NRCS