Labrador Tea

Other names

• In Latin: Rhododendron groenlandicum (Oeder) Kron & Judd;also called Ledum groenlandicum Oeder;Ledum – (former genus name) comes from the Greek word ledon, their name for another plant; groenlandicum - refers to the fact that it grows in Greenland.
• In English: Bog Labrador-tea, swamp tea, Hudson’s Bay tea, Haida tea
• In French: Thé du Labrador, thé velouté, bois de savane
• In Chipewyan: naghodhi
• In Cree: muskekopukwa
• In Slave: kotsuⁿdago(a^h)
  

Taxonomy

ERICACEAE (Heath family)

Description

• Form: This low evergreen shrub, about 0.3 m to 0.8 m tall, has many erect branches and distinctive narrow leaves with rolled-under edges. If often grows in dense colonies. The stems often appear bent, and the leaves often cluster very closely at the tip. The plant spreads roots in the organic layer with rhizomes. It reproduces generally by spreading vegetatively, and less commonly, from seed.

• Leaves: One only needs a leaf to identify this plant. The leathery leaves, dotted with resinous glands, 1 cm to 5 cm long, are fragrant with a pungent scent when crushed. Check under the rolled-down leaf edges for a woolly mat of hairs on the undersurface. (New leaves have white hairs; mature leaves have reddish hairs.)

• Flowers: Numerous small white flowers appear in a showy, loose, umbrella-like cluster at the branch tips. The five flaring petals are up to 8 mm long. Each of the many flowers has five to seven stamens that reach far above the petals, making the flower cluster appear fuzzy. The flowers are aromatic, with the scent coming from its oil, ledol.

• Fruit: Each flower forms a dry, many-seeded, drooping capsule. The capsules are small (5 mm to 7 mm long), fuzzy, 5- parted, narrowly oval in shape, and are tipped with a persistent style.

In the far north, observers can also report on the related Northern Labrador tea (Rhododendron tomentosum subsp. subarcticum (Harmaja) G.D. Wallace, formerly Ledum decumbens (Aiton) Lodd. ex Steud.). It is essentially a dwarf version of R. groenlandicum. It is smaller (only up to 50 cm), often more prostrate, has shorter, narrower leaves and flower stalks with reddish rather than white hairs. The flowers have 8-11 stamens instead of 5-7. It occurs in similar areas, though farther north and at higher elevation heath and tundra, up to 1800 m. It is often found with other dwarf shrubs or moss/lichen heaths, forming dense stands. It is found especially in Yukon, the Northwest Territories, Nunavut, and Labrador.

Distribution

The plant occurs in North America from Greenland and Labrador across to Alaska, as far north as treeline. It is absent from the far North and the dry prairies. It often grows in dense colonies. It is also found in the northern United States.

Habitat

Labrador Tea is found in peatlands, tundra and moist coniferous woods and is a frequenter of swamps, muskegs and bogs, though it may be found in drier, rocky places in the mountains. The plant is an indicator of wet, usually very acidic and nutrient poor organic soils and is widespread at low and medium elevations.

Labrador tea is dominant or co-dominant in a variety of habitats. It may occur as an understory component in open or closed forest habitats, primarily with black or white spruce. It may also dominate or co-dominate in low shrub types, bogs, muskegs or open tundra. In the Yukon it can commonly co-dominate with shrub birch (Betula glandulosa).

Labrador tea is an important component of woodland understories through the early, mid and late seral stages of succession. It is often abundant in the shaded portion of a forest, but can reach its greatest cover in bogs.

It can generally survive fire, as the rhizomes are found deep in the organic layer and it is often found in areas too wet to burn. It is one of the first plants to recolonize after fire and grows rapidly.

How to Observe

1. Mark a plot of Labrador Tea, about one metre by one metre in size.
2. Record these dates:
   • First bloom: In at least three places in the plot of plants under observation, the first flowers have opened completely.
   • Mid bloom: Approximately half (50%) of the flowers on the plants under observation are open.

Life Cycle

Labrador tea is a slow growing evergreen shrub. New shoots of the season originate at the base of the flower cluster.

Phenology

This species flowers from late May to mid-July, its seeds ripen in the fall and the capsules are often persistent on the plant for several months.

In northern Canada, note that Northern Labrador tea, Rhododendron tomentosum subsp.subarcticum (formerly Ledum decumbens), can flower 7-10 days later than R. groenlandicum, in areas where both occur in the subarctic (Derek Johnson, pers. comm.).

Northern observers: Please report which species you are observing.

Ecology

Leaves: The thick leathery texture, the rolled edges and the woolly mats of reddish hairs on the undersurface are all adaptations that help to conserve moisture.

There is some evidence that this plant is allelopathic, inhibiting germination or growth of other nearby plants.

This plant is an alternate host to a fungal disease called spruce needle rust. The young leaves of Labrador tea become infected in the fall; look for evidence of the orange fungus and powdery orange spores on the leaves.

A useful ecological indicator species, this species is characteristic of acidic soils with high moisture and poor nutrient regimes. It is often associated with black spruce.

Labrador tea leaves and twigs are browsed by caribou and moose. This plant is especially important for woodland caribou from the time other shrubs lose their leaves in the fall until green sedges appear in the spring. Labrador tea also provides cover for a variety of small mammals.

Human Uses, Ethnobotany

The plant was presumably used as a tonic by First Nations people. It is thought that it was the Europeans who introduced the idea of using the plant more commonly as a tea. In the fur-trading era, the French Canadian “coureurs-de-bois” used Labrador tea to extend their supplies of black tea. The leaves and the flowers can both be used for tea, either fresh or dried, and the leaves can be picked all year.

To make a tea rich in Vitamin C, steep one heaping teaspoonful of leaves or flowers per person in boiling water for 5 minutes. The colour should be a clear, pale amber-orange. It can also be used to stretch black tea for a more aromatic drink.

CAUTION: The tea can cause drowsiness and can act as a strong diuretic, cathartic or cause intestinal disturbances. The tea should be used infrequently and strong tea avoided. Like other plants in the Heath family, it contains an andromedotoxin that can cause adverse effects including headache, cramps, indigestion, vomiting, and even death. It also contains narcotic substances and an active oil ledol that may have a restorative effect like caffeine but which can cause cramps and paralysis in large doses.

Do not confuse this plant with Rhododendron tomentosum subsp. subarcticum (Northern Labrador tea), Kalmia microphylla (Bog Laurel) or Andromeda polifolia (Bog Rosemary), as all three contain toxic alkaloids known to be poisonous to livestock. All three lack the fuzz on the underside of mature leaves and the flowers of Kalmia and Andromeda are pink.

The leaves were used medicinally to treat a variety of ailments, including diarrhea, bad breath, pneumonia, eye infections, difficulty urinating, tension and kidney ailments, among more. It was used in a warm bath to treat arthritis of the hands. To relieve migraines, the tea was drunk and dried leaves were wrapped and placed on the head overnight. To treat excess hair loss, a tea concoction was drunk and also applied to the hair. The leaves were also chopped and applied to burns, which were said to heal more rapidly. Other uses are associated with the pungent odor: the dried leaves were stored with grain to repel rodents, and extracts of the leaves were used to create an insect repellent. A brown dye can be extracted from the leaves. Labrador tea has the ability to concentrate zinc and copper, and thus has value in geo-botanical studies.

Horticulture (Use in the Garden)

Labrador tea has been introduced into old country gardens as an ornamental shrub.

References

Clark, L.J. 1976. Wild flowers of the Pacific Northwest. Ed. by J. Trelawny. Gray’s Publishing Ltd., Sidney, British Columbia.

Hiratsuka, Y. D.W. Langor, and P.E. Crane. 1995. A field guide to forest insects and diseases of the prairie provinces. Nat. Resour. Can., Can. Forest Service Special Rep. 3. Edmonton, Alberta.

Kershaw, L. 2000. Edible and medicinal plants of the Rockies. Lone Pine Publishing. Edmonton.

MacKinnon, A., J. Pojar and R. Coupe. 1992. Plants of northern British Columbia. B.C. Ministry of Forests and Lone Pine Publishing.

Marie-Victorin, F. 1964. Flore Laurentienne. Les Presses de l’Université de Montreal. Montreal.

Marles, Robin J. et al. 2000. Aboriginal plant use in Canada’s Northwest Boreal Forest. Natural Resources Canada. UBC Press. Vancouver.

Porsild, A.E. and W.J. Cody. 1980. Vascular plants of continental Northwest Territories, Canada. National Museum of Natural Sciences, National Museums of Canada. Ottawa.

Ringius, G.S. and R.A. Sims. 1997. Indicator plant species in Canadian forests. Canadian Forest Service, Natural Resources Canada. Ottawa.

Turner, N.J. 1987. Food plants of British Columbia Indians – coastal peoples. British Columbia Provincial Museum. Victoria.

Thanks to Beth Cornish, Jen Staniforth, Kim Monson, and Laura Frost, who all contributed to the text.