''Rhododendron tomentosum'' ( syn. ''Ledum palustre''), commonly known as marsh Labrador tea, northern Labrador tea or wild rosemary, is a

flowering plant Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (), commonly called angiosperms. The term "angiosperm" is derived from the Greek words ('container, vessel') and ('seed'), and refers to those plants th ...

in the subsection '' Ledum'' of the large genus '' Rhododendron'' in the family

Ericaceae The Ericaceae are a family of flowering plants, commonly known as the heath or heather family, found most commonly in acidic and infertile growing conditions. The family is large, with c.4250 known species spread across 124 genera, making it th ...

Description

It is a low shrub growing to 50 cm (rarely up to 120 cm) tall with

evergreen In botany, an evergreen is a plant which has foliage that remains green and functional through more than one growing season. This also pertains to plants that retain their foliage only in warm climates, and contrasts with deciduous plants, whic ...

leaves 12–50 mm long and 2–12 mm broad. The

flower A flower, sometimes known as a bloom or blossom, is the reproductive structure found in flowering plants (plants of the division Angiospermae). The biological function of a flower is to facilitate reproduction, usually by providing a mechani ...

s are small, with a five-lobed white corolla, and produced several together in a

corymb Corymb is a botanical term for an inflorescence with the flowers growing in such a fashion that the outermost are borne on longer pedicels than the inner, bringing all flowers up to a common level. A corymb has a flattish top with a superficial ...

3–5 cm diameter. They emit strong smell to attract bees and other pollinating insects.

Distribution and habitat

It grows in northern latitudes in North America,

Greenland Greenland ( kl, Kalaallit Nunaat, ; da, Grønland, ) is an island country in North America that is part of the Kingdom of Denmark. It is located between the Arctic and Atlantic oceans, east of the Canadian Arctic Archipelago. Greenland i ...

Canada Canada is a country in North America. Its ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, covering over , making it the world's second-largest country by tot ...

, and

Alaska Alaska ( ; russian: Аляска, Alyaska; ale, Alax̂sxax̂; ; ems, Alas'kaaq; Yup'ik: ''Alaskaq''; tli, Anáaski) is a state located in the Western United States on the northwest extremity of North America. A semi-exclave of the U.S. ...

, in

Europe Europe is a large peninsula conventionally considered a continent in its own right because of its great physical size and the weight of its history and traditions. Europe is also considered a subcontinent of Eurasia and it is located entirel ...

in the northern and central parts, and in

Asia Asia (, ) is one of the world's most notable geographical regions, which is either considered a continent in its own right or a subcontinent of Eurasia, which shares the continental landmass of Afro-Eurasia with Africa. Asia covers an are ...

south to northern China,

Korea Korea ( ko, 한국, or , ) is a peninsular region in East Asia. Since 1945, it has been divided at or near the 38th parallel, with North Korea (Democratic People's Republic of Korea) comprising its northern half and South Korea (Republic o ...

and Japan. It grows in peaty soils, shrubby areas, moss and lichen

tundra In physical geography, tundra () is a type of biome where tree growth is hindered by frigid temperatures and short growing seasons. The term ''tundra'' comes through Russian (') from the Kildin Sámi word (') meaning "uplands", "treeless mou ...

Chemical compounds

All parts of the plant contain poisonous

terpenes Terpenes () are a class of natural products consisting of compounds with the formula (C5H8)n for n > 1. Comprising more than 30,000 compounds, these unsaturated hydrocarbons are produced predominantly by plants, particularly conifers. Terpenes ar ...

that affect the

central nervous system The central nervous system (CNS) is the part of the nervous system consisting primarily of the brain and spinal cord. The CNS is so named because the brain integrates the received information and coordinates and influences the activity of all p ...

. First symptoms of

overdose A drug overdose (overdose or OD) is the ingestion or application of a drug or other substance in quantities much greater than are recommended.

are

dizziness Dizziness is an imprecise term that can refer to a sense of disorientation in space, vertigo, or lightheadedness. It can also refer to disequilibrium or a non-specific feeling, such as giddiness or foolishness. Dizziness is a common medical c ...

and disturbances in movement, followed by

spasm A spasm is a sudden involuntary contraction of a muscle, a group of muscles, or a hollow organ such as the bladder. A spasmodic muscle contraction may be caused by many medical conditions, including dystonia. Most commonly, it is a muscle c ...

nausea Nausea is a diffuse sensation of unease and discomfort, sometimes perceived as an urge to vomit. While not painful, it can be a debilitating symptom if prolonged and has been described as placing discomfort on the chest, abdomen, or back of the ...

, and

unconsciousness Unconsciousness is a state in which a living individual exhibits a complete, or near-complete, inability to maintain an awareness of self and environment or to respond to any human or environmental stimulus. Unconsciousness may occur as the re ...

. Among the plant's terpenes is ledol a cyclic alcohol with deliriant effects, although poisonous in large doses.

Similar species

This species is not to be confused with the traditionally-used one ''

Rhododendron groenlandicum ''Rhododendron groenlandicum'' (bog Labrador tea, muskeg tea, swamp tea, or in northern Canada, Hudson's Bay tea; formerly ''Ledum groenlandicum'' or ''Ledum latifolium'') is a flowering shrub with white flowers and evergreen leaves that is used ...

'', found throughout Northern North America.

Uses

Herbal medicine

''Rhododendron tomentosum'' is used in

herbalism Herbal medicine (also herbalism) is the study of pharmacognosy and the use of medicinal plants, which are a basis of traditional medicine. With worldwide research into pharmacology, some herbal medicines have been translated into modern reme ...

to make an

herbal tea Herbal teas, also known as herbal infusions and less commonly called tisanes (UK and US , US also ), are beverages made from the infusion or decoction of herbs, spices, or other plant material in hot water. Oftentimes herb tea, or the plain term ...

called "

Labrador tea Labrador tea is a common name for three closely related plant species in the genus ''Rhododendron'' as well as an herbal tea made from their leaves. All three species are primarily wetland plants in the heath family. The herbal tea has been a ...

". Some schools of homeopathy consider ''Rhododendron tomentosum'' to be a specific remedy for puncture wounds produced by sharp-pointed objects or bites. However, no objective material benefit has ever been documented in any properly controlled study to date.

Other uses

Marsh Labrador tea has traditionally been used as a

gruit Gruit (alternately grut or gruyt) is a herb mixture used for bittering and flavouring beer, popular before the extensive use of hops. The terms gruit and grut ale may also refer to the beverage produced using gruit. Historically, gruit is the te ...

in brewing

beer Beer is one of the oldest and the most widely consumed type of alcoholic drink in the world, and the third most popular drink overall after water and tea. It is produced by the brewing and fermentation of starches, mainly derived from ce ...

in the

Middle Ages In the history of Europe, the Middle Ages or medieval period lasted approximately from the late 5th to the late 15th centuries, similar to the post-classical period of global history. It began with the fall of the Western Roman Empire ...

. Due to its strong fragrance, it has also formerly been used as a natural deterrent against clothes moths, also mosquitos and bugs in general, in Scandinavia and in Eastern Europe.

References

External links

*
Flora of China: ''Ledum palustre''USDA PLANTS database: ''Ledum palustre''Den virtuella floran: ''Distribution''
{{Authority control tomentosum Herbal tea Medicinal plants Flora of Japan Flora of Korea Flora of Norway Flora of Germany Flora of Russia Flora of North America Flora of Greenland