Labrador Tea - Rhododendron groenlandicum

Family: Ericaceae (Crowberry family) ^[E-flora]

Synonyms

• Ledum groenlandicum ^{[IFBC-E-flora]}
• Ledum palustre var. latifolium (Jacq.) Michx. ^{[IFBC-E-flora]}
• L. latifolium. ^[PFAF]
• L. pacificum. ^[PFAF]
• L. palustre groenlandicum. (Oeder.)Hulten. ^[PFAF]

Suitable for: light (sandy), medium (loamy) and heavy (clay) soils. Suitable pH: acid soils and can grow in very acid soils.
It can grow in full shade (deep woodland) semi-shade (light woodland) or no shade. It prefers moist or wet soil.^[PFAF]
Origin Status: Native ^{[IFBC-E-flora]}
General: Erect shrub; stems 0.5-1.5 m tall, rusty soft-hairy. ^{[IFBC-E-flora]}
Leaves: Alternate, evergreen, leathery, oblong to lance-oblong or elliptic, (1.2) 2-6 cm long, 3-15 mm wide, margins strongly to slightly rolled under, tips blunt, upper surface deep green, appearing somewhat wrinkled, glabrous to slightly reddish soft-hairy, copiously rusty or yellowish soft-hairy beneath; stalks 1-5 mm long.^{[IFBC-E-flora]}
Flowers: In terminal umbrella-like clusters; flower stalks (0.6) 1.2-2.5 cm long, with short, white hairs (rarely with a few contorted, reddish hairs), often glandular, curved in fruit; corollas white, wheel-shaped, 10-12 mm across, the 5 distinct petals spreading, oblong, and 5-8 mm long; calyces less than 1 mm long, minutely white-hairy on margins, sometimes glandular; stamens 5-8, slightly exceeding the styles, filaments glabrous or sometimes hairy at the base.^{[IFBC-E-flora]}
Fruits: Capsules, narrowly egg-shaped, 4-7 mm long, minutely hairy.^{[IFBC-E-flora]}
Habitat: Bogs and moist to wet forests in the lowland and montane zones.^{[IFBC-E-flora]} Cold bogs and montane coniferous woods[4, 50]. ^[PFAF]
Range: common throughout most of BC, infrequent in SC BC; N to AK, E to NF, and S to OR, MN, PA, and NJ.^{[IFBC-E-flora]} Eastern and Northern N. America to Greenland. A rare garden escape in Britain.^[PFAF]

Hazards

"In our experience Labrador tea is as safe as regular tea or coffee, but it is said by some to produce drowsiness. We have never experienced such an effect, which may be due to physiological sensitivity in certain individuals or may in some cases be purely psychological. In any case, we recommend that you drink the tea only in moderate quantities and in low concentrations; do not boil the leaves for longer than 10 minutes." ^[Coffee]

• The National Dispensatory records that the leaves in full doses cause headache, vertigo, restlessness and a peculiar delirium.[HuronSmith Zuni]
• Andromedotoxin: "Many plants in the heather family, including Ledum species, contain a poisonous compound called andromedotoxin, which if consumed in large concentrations can be harmful, causing vomiting, illness and even death. Labrador-tea evidently has less andromedotoxin than other, related plants such as laurels (Kalmia spp.) and rhododendrons and azaleas (Rhododendron spp.); nevertheless, Labrador-tea should be used only in moderation, and in relatively dilute infusions." ^{[Turner, Kuhnlein]}
• Ledel: Plants contain a narcotic toxin called Ledel. This toxin only causes problems if the leaves are cooked for a long period in a closed container[172]. ^[PFAF]
• Toxic Lookalikes: Two closely related shrubs, Ledum glandulosum Nutt. (sometimes called trapper's tea) and Kalmia polifolia Wang. (swamp laurel), both widespread in Canada, are reputedly toxic in concentrated doses and have apparently killed browsing livestock. Trapper's tea produces a rather bitter drink of inferior quality. These species are similar in growth form and habitat to Labrador tea, but neither has the characteristic fuzz on the undersides of the leaves, and Kalmia has pink blossoms. ^[Coffee]

Edible Uses

L. groenlandicum was used by virtually all indigenous peoples of B.C. ^{[Turner, Kuhnlein]}

• Tea: The use of Labrador-tea as a beverage is very widespread in Canada. The Gitksan were said originally to have used it only as a medicinal tonic, and other groups also used the tea as medicine. Explorer Samuel Hearne reported in the 1770's that Labrador-tea was ".. .much used by the lower class of the [Hudson's Bay] Company's servants as tea; and by some is thought very pleasant. But the flower is by far the most delicate, and if gathered at the proper time, and carefully dried in the shade, will retain its flavor for many years and make a far more pleasant beverage than the leaves".^{[Turner, Kuhnlein]} Of all the wild substitutes for tea available to Canadians this is probably the most popular and widely used. It was and still is used by Indian and Eskimo peoples across Canada. In the past it was used by many explorers. settlers, traders, and trappers. ^[Coffee]
  • Leaves and sometimes the whole leafy twigs and flowers, of both species were used, fresh or dried, for tea. ^{[Turner, Kuhnlein][Coffee]} Fragrant and soothing [2, 4, 95, 102, 172]. ^[PFAF]
  • Harvesting: Gathered year-round. ^{[Turner, Kuhnlein]} The methods of collecting and preparing them vary widely. Some people say that the leaves should be collected in the spring before the flowers appear; others say that the best time for harvesting is in the fall or late winter, when the leaves are mature and reddish-brown in colour. We recommend that you collect the young leaves in early summer. ^[Coffee]
    
  • Preparation: To make tea, they were boiled for half an hour or more, until the tea was dark brown, or simply steeped in boiling water. Used fresh, but usually dried and stored. ^{[Turner, Kuhnlein]} The leaves can be used fresh or, for storage, can be dried in the sun, over a fire, or in an oven. Some native peoples in western Canada used to steam the leaves in underground pits until they turned dark brown. ^[Coffee]
    
  • Dried: Place them in small quantities in paper bags, and hang them up in a warm place until they are completely dry and brittle, then store them in tightly sealed containers. Treated in this way they will keep for several years. ^[Coffee]
  • We think the best method is to place a generous handful of leaves in about 1 L (4 cups) of boiling water and allow them to simmer a short time, perhaps 5 minutes. ^[Coffee]
    
  • Combinations: The North American Indians would often flavour this tea with the roots of liquorice fern, Polypodium glycyrrhiza [256]. When lemon is added they can be used as iced tea[183]. ^[PFAF] Today, people usually sweeten this tea with sugar or honey. Sometimes it's mixed with wild mint or rose hips.^{[Turner, Kuhnlein]} You may find the flavour is enhanced by adding a few drops of lemon juice and a little honey. You can also use sugar and cream, but they tend to mask the delicate flavour. ^[Coffee]
    
  • Properties: The spicy leaves make a very palatable and refreshing tea[183].^[PFAF] The resulting tea has a yellowish-green tint and a sweet, flower-like fragrance reminiscent of jasmine tea. People who prefer it stronger leave it on the stove for several hours, but we do not recommend this procedure. ^[Coffee]
    
  • Caution: Some caution is advised, see the notes above on toxicity. It would be better to brew the tea in cold water by leaving it in a sunny place, or to make sure that it is brewed for a short time only in an open container. ^[PFAF]
• Leaves:
  • Beer: The leaves were once added to beer in order to make it heady[183]. ^[PFAF] "Labrador tea, while not as strong in its effects as wild rosemary, may still be used similarly both in brewing and in herbal practice." [Buhner SHHB]
    
  • Spice: The leaves are used as a flavouring, they are a bayleaf substitute [172]. ^[PFAF] Chewed as a flavoring. Boiled with strong-tasting meat, such as bear meat, as a spice.^{[Turner, Kuhnlein]}
    

Other Uses

• Tobacco Adulterant: Leaves smoked as a "narcotic". ^{[Pharmacotheon]} The Parry Island Ojibwa near Lake Huron in North America smoked the leaves of this species when tobacco (Nicotiana spp.) was scarce (Jeaness 1935). ^[UAPDS]
• Tannin: The leaves contain tannin [4]. ^[PFAF]
• Insecticide:
  • Leaves: The leaves are hung up in the clothes cupboard in order to repel insects [4].^[PFAF] Because of its strong scent, Europeans used the leaves for keeping rodents out of corn cribs and repelling fleas, clothes moths, and other household insects. ^[Coffee] "...fresh twigs have been placed among woollen clothes to keep moths away from them." ^{[HuronSmith Zuni]}
  • Decoction: A strong decoction of the leaves, or a tincture, is used to kill lice, mosquitoes, fleas and other insects [4, 207, 238]. ^[PFAF] "A decoction of the leaves has been used as a vermin exterminator..." [HuronSmith Zuni]
• Rodenticide: The branches are also placed among grain in order to keep mice away [4]. ^[PFAF]
• Dye: A brown dye is obtained from the plant [257]. ^[PFAF]

Medicinal Uses

• Tea: tea was employed medicinally by several native North American Indian tribes who used it to treat a variety of complaints[257]. ^[PFAF] An extract made from boiling the leaves in water was taken for spitting of blood, and was used to wash open sores and wounds which would not heal (Boas, 1966). [Turner&Bell2]
• The plant has been an important medicine to native peoples, and as a tea is considered especially good for colds, sore throats and headaches. ^[Coffee]
• "There is also a mention in Beardsley (1941) [58] about Labrador tea being a possible emetic, while Marles et al. (2000)recorded its use against bad breath, pneumonia, infants’ teething pain and rashes and eye infections." ^{[Jetter PBFA]}
• Dosage: 1 tsp dry leaf/cup water (APA). ^{[HMH Duke]}
• Birthing Aid: The plant is apparently a mild narcotic, it was taken by Indian women three times daily shortly before giving birth[207]^[PFAF]
• Leaves: Analgesic, blood purifier, diaphoretic, diuretic, pectoral and tonic[4, 172, 222, 257]. ^[PFAF]
  • Internally: A tea is taken internally in the treatment of headaches, asthma, colds, stomach aches, kidney ailments etc[222, 257]. ^[PFAF] "...crushed leaves used by Scandinavians to flavor schnapps—the alcoholic nightcap is used as a sleep aid." "...fresh leaves are chewed as a general tonic." ^{[Meuninck EWPUH]}
• Leaves & Roots
  • An ointment made from the powdered leaves or roots has been used to treat ulcers, cracked nipples, burns and scalds[257]. ^[PFAF] Powdered roots were applied to ulcers. ^{[Meuninck EWPUH]}
• Dermatological Aid: In modern herbalism it is occasionally used externally to treat a range of skin problems. ^[PFAF]
  • Externally, it is used as a wash for burns, ulcers, itches, chapped skin, stings, dandruff etc[222, 238, 257]. ^[PFAF] Alcohol extracts used to treat numerous skin conditions including inflammation, scabies, fungus, chiggers, and lice bites. ^{[Meuninck EWPUH]}

Phytochemistry

Crude Extract

"Our team has previously reported the phytochemical characterization of Labrador tea crude ethanolic extract [59]. In that study, we identified (+)-catechin (9), (−)-epicatechin (10), chlorogenic acid (50), myricitin (51), procyanidin B2 (52), procyanidin A1 (53) and several quercetin glycosides (quercetin-3-O-glucoside (45), quercetin-3-O-galactoside (46); rutin (25) and quercetin-3-O-rhamnoside (54))." ^{[Jetter PBFA]}

Pharmacology

"In our screening studies, it stimulated glucose uptake in muscle cells, but more importantly induced adipogenesis as strongly as the reference drug rosiglitazone [8]. This would mean less free fatty acids circulating and accumulating in insulin-sensitive tissues such as the liver and the muscle. Such activity is also associated with an improvement of insulin sensitivity." ^{[Jetter PBFA]}

Cultivation

"Requires a lime-free loam or peaty soil[1, 11]. Prefers a moist humus-rich acid soil in shade or semi-shade[200]. Plants flower more freely when grown in a sunny position. Plants grow better if they have certain fungal associations in the soil. The best way of providing this is to incorporate some soil from around well-growing established plants into the soil for the new plant[200]. Hardy to at least -15°c[200]. The leaves and the flowers are very aromatic[182, 245]. Plants benefit from removing the dead flowers before they set seed[188]. This prevents them putting too much energy into seed production at the expense of more flowers and leaves. This species is considered by some botanists to be no more than a sub-species of L. palustre[11, 50]. A good bee plant[4]." ^[PFAF]

Propagation

"Seed - surface sow in a shady part of the greenhouse in February or March[78, 113]. Another report says that the seed is best sown in the autumn as soon as it is ripe[188]. Germination is variable and can be quite slow. Prick out the seedlings into individual pots as soon as they are large enough to handle and grow the pots on in a shady frame for 18 months before planting them out into their permanent positions[78]. Cuttings of half-ripe wood, 5 - 8cm with a heel, July/August in a frame. Plant out in spring. Fair percentage[78]. Cuttings of mature wood, November/December in a frame[113]. Layering in the autumn. Takes 12 months[78]. Division." ^[PFAF]

• The flowers are hermaphrodite (have both male and female organs) and are pollinated by Bees. It is noted for attracting wildlife.^[PFAF]

Medicinal Harvesting:
"Harvesting of medicinal plants from wild populations is increasing worldwide, however, studies on sustainable harvesting techniques are lacking. In this exploratory study, we investigated the impact of leaf harvesting on (Oeder) Kron & Judd, a North American temperate shrub, used traditionally as a medicinal plant by the Cree Nation. The species is widely distributed, but Crees are worried that commercial harvesting could threaten local plant populations. Our study was conducted near the Cree Nation of Mistissini (James Bay, Northern Quebec). Three leaf harvest regimes were tested in 2008 and 2009: no harvest, all leaves harvested, and only old leaves harvested; each treatment was performed on 30 plants. The harvesting of all leaves had a negative impact on stem elongation after the first harvest, while leaf production and stem radial growth decreased after the second harvest. Two-thirds of the plants also died following the second regime of harvesting all leaves. The harvesting of old leaves had no significant impact on growth, leaf production, or survival of R. groenlandicum, even after 2 years of harvest. These results lead to the conclusion that sustainable harvest of this species is possible, but further study is required to make definite recommendations." ^{[MedHarvesting]}

Allelopathy - N Transformations Under Ledum palustre

"Ledum palustre and Ledum groenlandicum are late successional evergreen shrubs widely distributed in boreal ecosystems that are known to inhibit the growth of P. mariana and Picea glauca when they dominate the understory (Cole et al. 2003; Inderjit and Mallik 1996b). " ^{[Zeng ASA]}

"This interference has been related to the presence of plant secondary metabolites (Inderjit and Mallik 1997).... amendments of L. groenlandicum foliage and litter have been found to increase concentrations of phenolic compounds in the soil.... Mineral soils sampled under L. palustre canopy had a lower net N mineralization and N-to-C mineralization ratio, and a higher C mineralization compared to control soils, which was caused by higher gross ammonium immobilization rates (110.6% increase) compared to Ledum-free sites. ...soils sampled under L. palustre and amended with leachate showed similar responses. Thus, C compounds leached from L. palustre stimulated microbial activity when microbes use them as a substrate resulting in increases in soil N immobilization and decreases in N availability for vegetation." ^{[Zeng ASA]}

"...mild fires, clearcutting, or heavy spruce budworm defoliation in nutrient-poor black spruce or balsam fir (Abies balsamea (L.) Mill.) Kalmia forest can convert the forest community into Kalmia heath, and it can last for a very long time. If, on the other hand, the understory is predominantly Labrador tea (Ledum groenlandicum Oeder.), the growth inhibition of black spruce may last for 6-10 years, and after that the black spruce may regain the canopy dominance [47]." ^{[Mallik CEP]}

Rhododendron

Family: Ericaceae - Heath

Shrub to tree, glabrous, hairy, and/or with glandular scale-like hairs. Stem: prostrate to erect, bark thin, sometimes peeling or shredding. Leaf: alternate, evergreen or deciduous, ovate to obovate to elliptic, margin entire, flat to rolled under. Inflorescence: raceme, 1–many-flowered, bracts green to red-brown. Flower: sepals, petals generally 5, corolla radial to bilateral, 1–5 cm, petals free to ± fused, spots or blotch present or 0; anther awns 0; ovary superior. Fruit: capsule, septicidal, dehiscing base to tip or tip to base, placentas axile. Seed: many, fusiform, ± flat to not, wings and/or tails present or 0.
± 1000 species: northern hemisphere, tropical Asia, to Australia. (Greek: rose tree)
Unabridged references: [Chamberlain 1982. Notes Roy. Bot. Gard. Edinburgh 39:209–486; Cullen 1980 Notes Roy. Bot. Gard. Edinburgh 39:1–207] ^[Jepson]

Local Species;

1. Rhododendron albiflorum - white-flowered rhododendron ^{[E-flora][PCBC][TSFTK]}
2. Rhododendron groenlandicum - Labrador tea ^{[E-flora][PCBC][TSFTK]}
3. Rhododendron macrophyllum - Pacific rhododendron ^{[E-flora][PCBC][TSFTK]}

R.albiflorum
A shade-tolerant/intolerant, montane to alpine, Western North American deciduous shrub distributed more in the Cordilleran than the Pacific region. Occurs predominantly in continental subalpine boreal climates on moderately dry to fresh, nitrogen-poor soils (Mor humus forms); its occurrence increases with increasing continentality and decreases with increasing latitude. Common and often dominant on water-shedding sites in open­canopy coniferous forests in the coast-interior ecotone; often on decaying coniferous wood. Typically associated with Barbilophozia floerkei, B. lycopodioides, Rhytidiopsis robusta, and Vaccinium membranaceum. An oxylophytic species characteristic of subalpine continental forests.(IPBC)[E-flora]

Habitat / Range
Dry to wet forests and openings in the montane and subalpine zones; common in C and S BC; E to SW AB, and S to OR and W MT.

R.macrophyllum
Habitat / Range
Mesic to moist forests in the lowland and montane zones; locally frequent in the Cascade Mountains, rare on S Vancouver Island; S to MT and N CA.[IFBC-E-flora]

Uses of Related Sp.

• Ledum palustre L. (Ericaceae). crystal tea.: In eastern Kazakhstan, Russia, Siberia, and Ukraine, the leaves of this plant were sometimes burned as a fumigant to drive away insects (Minaeva 1991). ^[UAPDS]

References

• [E-flora] http://linnet.geog.ubc.ca/Atlas/Atlas.aspx?sciname=Rhododendron groenlandicum&redblue=Both&lifeform=3 [Accessed: September 21, 2014]
• [2] Personal Observation and notes. http://www.phytoday.org
  
• [MedHarvesting] Impacts of experimental leaf harvesting on a North American medicinal shrub, Rhododendron groenlandicum. Tendland, Youri; Pellerin, Stéphanie; Haddad, Pierre; Cuerrier, Alain, Botany. Mar 2012, Vol. 90 Issue 3, p247-251. 5p.
  
• [PFAF] Ledum groenlandicum Plants for a future, Accessed September 22, 2014