Labrador tea is a common name for three closely related plant species in the genus Rhododendron as well as a herbal tea made from their leaves.
All three species are primarily wetland plants in the heath family. The herbal tea has been a favorite beverage among Athabaskan First Nations and Inuit.
All three species used to make Labrador tea are low, slow-growing shrubs with evergreen leaves:
The leaves are smooth on top with often wrinkled edges, and fuzzy white to red-brown underneath. [1]
R. tomentosum, R. groenlandicum, and R. neoglandulosum can be found in wetlands and peat bogs. [1]
The Athabaskans and other indigenous peoples brew the leaves as a beverage. [1] The Pomo, Kashaya, Tolowa and Yurok of Northern California boil the leaves of western Labrador tea similarly, to make a medicinal herbal tea to help with coughs and colds. [2] Botanical extracts from the leaves have been used to create natural skin care products by companies in Quebec and Newfoundland and Labrador. Others use Labrador tea to spice meat by boiling the leaves and branches in water and then soaking the meat in the decoction.[ citation needed ]
During the eighteenth century, German brewers used R. tomentosum while brewing beer to make it more intoxicating, but it became forbidden because it led to increased aggression. [1]
There is no sufficient data that demonstrates Labrador tea is safe to consume as toxicity varies across species and localities. Excessive consumption is not recommended due to diuresis, vomiting, dizziness, and drowsiness. [1] Large doses can lead to cramps, convulsions, paralysis, and, in rare cases, death. [1]
Toxicity occurs due to terpenoid ledol found in all Labrador tea species. R. groenlandicum has the lowest toxicity due to lower levels of ledol. Grayanotoxins are also present, but few lethal human cases of poisoning due to grayanotoxins in Labrador tea have been documented. However, lethal poisonings have been documented in livestock. [1]
Labrador tea is slow-growing, so new single leaves are collected in spring from multiple plants to avoid damaging individual plants every other year. [1]
Herbal teas, also known as herbal infusions and less commonly called tisanes, are beverages made from the infusion or decoction of herbs, spices, or other plant material in hot water; they do not usually contain any actual tea. Often herb tea, or the plain term tea, is used as a reference to all sorts of herbal teas. Many herbs used in teas/tisanes are also used in herbal medicine. Some herbal blends contain actual tea.
Rhododendron is a very large genus of about 1,024 species of woody plants in the heath family (Ericaceae). They can be either evergreen or deciduous. Most species are native to eastern Asia and the Himalayan region, but smaller numbers occur elsewhere in Asia, and in North America, Europe and Australia.
Grayanotoxins are a group of closely related neurotoxins named after Leucothoe grayana, a plant native to Japan originally named for 19th century American botanist Asa Gray. Grayanotoxin I is also known as andromedotoxin, acetylandromedol, rhodotoxin and asebotoxin. Grayanotoxins are produced by Rhododendron species and other plants in the family Ericaceae. Honey made from the nectar and so containing pollen of these plants also contains grayanotoxins and is commonly referred to as mad honey.
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Ledum was a genus in the family Ericaceae, including 8 species of evergreen shrubs native to cool temperate and subarctic regions of the Northern Hemisphere and commonly known as Labrador tea. It is now recognised as a subsection of section Rhododendron, subgenus Rhododendron, of the genus Rhododendron.
Rhododendron groenlandicum is a flowering shrub with white flowers and evergreen leaves that is used to make a herbal tea.
Rhododendron tomentosum, commonly known as marsh Labrador tea, northern Labrador tea or wild rosemary, is a flowering plant in the subsection Ledum of the large genus Rhododendron in the family Ericaceae.
Kalmia polifolia, previously known as Kalmia glauca and commonly called bog laurel, swamp laurel, or pale laurel, is a perennial evergreen shrub of cold acidic bogs, in the family Ericaceae. It is native to north-eastern North America, from Newfoundland to Hudson Bay southwards.
Rhododendron luteum, the yellow azalea or honeysuckle azalea, is a species of flowering plant in the heath family Ericaceae, native to southeastern Europe and southwest Asia. In Europe, it occurs from southern Poland and Austria, south through the Balkans, and east to southern Russia; and in Asia, east to the Caucasus.
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Rhododendron columbianum, commonly known as western Labrador tea, swamp tea, or muskeg tea, is a shrub that is widespread in the western United States and in western Canada, reported from British Columbia, Alberta, Washington, Oregon, Idaho, California, Montana, Wyoming, Utah, Nevada, and Colorado. It grows in wet places from sea level up to 3,500 m (11,000 ft). It was formerly known as Ledum columbianum. Its origins date back to the late Pliocene.
Ledol is a poisonous sesquiterpene that can cause cramps, paralysis, and delirium. Caucasian peasants used Rhododendron plants for these effects in shamanistic rituals.
Chrysomyxa nagodhii is a species of rust fungus in the family Coleosporiaceae. It was described as new to science by Canadian mycologist Patricia E. Crane in 2001. It probably occurs throughout the range of Ledum decumbens and Rhododendron groenlandicum. On Picea, spermogonia and aecia occur on distinct rusty yellow bands on current-year needles.
Kathleen Anne Kron is a retired biology professor from Wake Forest University. She is known for her research on Ericaceae, a family of flowering plants.