Flora of the Canadian Arctic Archipelago


S.G. Aiken, M.J. Dallwitz, L.L. Consaul, C.L. McJannet, R.L. Boles, G.W. Argus, J.M. Gillett, P.J. Scott, R. Elven, M.C. LeBlanc, L.J. Gillespie, A.K. Brysting, H. Solstad, and J.G. Harris

Ledum palustre L. subsp. decumbens (Aiton) Hultén

English: Labrador tea, muskeg tea.

Ericaceae, Bilberry family.

Published in Kungl. Sv. Vetensk.-Akad. Handl., ser. 3, 8, 2: 8. 1930.

Type: Described from northern Canada: Hudson Bay.

Synonymy. Ledum palustre L. var. decumbens Aiton, Hort. Kew. 2: 65. 1789.

Ledum decumbens (Aiton) Lodd. ex Steud., Nomencl. Bot., ed. 2, 2: 20. 1841.

Rhododendron subarcticum Harmaja, Ann. Bot. Fenn. 27: 203. 1990.

Rhododendron tomentosum (Stokes) Harmaja subsp. subarcticum (Harmaja) G.D.Wallace, Madroño 39: 77. 1992.

Vegetative morphology. Plants 10–20(–30) cm high; shrubs; low shrubs (usually), or dwarf shrubs. Aerial stems erect, or ascending, or decumbent. Aerial stem trichomes spreading. Leaves present; distributed along the stems; alternate; persistent. Stipules absent (prominent leaf bud scales present). Petioles present (tiny), or absent; 1–2 mm long; hairy; woolly. Petiole hairs spreading; wavy (hairs in the apical growing region of each stem are rusty brown; hairs on previous season's petioles are colourless or white). Leaf blade bases truncate, or attenuate (slightly). Blades 6–15 mm long, 1–2 mm wide, spreading or divaricate or reflexed, linear, revolute, veins pinnate. Blade adaxial surface without sessile glands, glabrous. Blade abaxial surface hairy (with dense brown hairs along the midvein), hairs tomentose, hairs very dense, hairs rust-coloured, hairs curved or wavy, hairs spreading. Blade margins entire, glabrous; apices rounded.

Reproductive morphology. Flowering stems solitary. Flowers in inflorescences. Inflorescences with flowers in umbels; lateral. Pedicels present. Bract leaves (5–)10–20 mm long. Flowers per inflorescence 5–15(–20); small (individual flowers, the cluster of flowers 1–2.5 cm in diameter). Sepals conventional; 5; free, or fused (at the base); green, or brown. Calyx rotate; with sessile glands; hairy (sparsely). Calyx hairs non-glandular (hairs among the sessile glands); brown (rusty). Petals conventional; free; 5 (usually); white (usually), or pink (rarely); obovate; slightly lobed or undulating; 2–3 mm long; 2–3 mm wide. Stamens 10. Anthers yellow. Anthers opening with a terminal pore. Anthers 0.8–1 mm long (without the horns found in some other Ericaceae species). Nectaries present. Ovary superior; carpels 5; syncarpous. Ovaries ovate; glabrous (and with sessile glands). Styles 1. Placentation axile. Ovules per ovary 15–20. Fruit stalked; stalk 10–15 mm long; with calyx persisting; dry; a capsule; spherical; brown; 2–3.5 mm long; 1–3.5 mm wide; glabrous and covered with papillae; surface appearing veinless; not distinctly flattened; dehiscent; teeth 5 (splitting from the pedicel end and remaining together at the style, that is, opening like an umbrella). Seeds numerous.

Chromosome information. 2n = 26 and 52.

2n (2x) = 26. Zhukova (1980, southern Chukotka);

2n (4x) = 52. Hagerup (1941a, Greenland?); Löve (1954b); Jørgensen et al. (1958, Greenland); Löve and Löve (1975, 1982a, Arctic Canada); Zhukova and Petrovsky (1976, western Chukotka, 1987b, northeastern Asia).

Ploidy levels recorded 2x and 4x.

Indigenous knowledge. Inuit names for this species are qijuktaaqpait (Baffin), meaning "a large amount of fuel for a fire" (Ootoova et al. 2001), and mamaittuqutiit (Nunavik).

Medicinal teas are made from the leaves to help general stomach ache, to strengthen a person after much bleeding, and to ease breathing for people with tuberculosis or less serious ailments. Labrador tea leaves may be chewed, placed on the chest, or mixed with seal fat in an ointment and rubbed on the chest (Anon 1984). Inhaling the vapours from the tea helps to clear congested nasal passages. The Inuit of Baffin Island used the stems as a sort of chewing tobacco, and the leaves were put in the smoking mixture. Labrador tea is picked all year round, though it is stronger in fall and winter. "It doesn’t die but like an animal, such as a dog, it keeps its fur(leaves) all winter. In the spring it develops new fur". The older the plant the better it is (Anon 1984).

They are used to treat toothaches and eye disorders. Labrador tea can heal canker sores in the mouth if you place the leaves on them. The stems and leaves could also be boiled for tea and used to treat sore throats. They are also known to moisten very dry hands (Ootoova et al. 2001).

Anderson (1939) noted that the plant occurred "all over the tundra" in Alaska, and at that time, was generally used for tea.

Andre and Fehr (2000) reported that Gwich'in people picked the leaves and stems all year round for tea and also used the white flowers for tea in the spring. Some people include the root of the plant to make a more concentrated medicinal drink. This muskeg tea is considered good for children and is known to be a relaxant and high in vitamin C. Inhaling the steam from this tea can help clear congested nasal passages. The tea can be made, cooled, and jarred for later use, but elders advise against keeping muskeg tea for more than a few days. Boiling or steeping the tea for more than 10 minutes is not recommended because of some of the chemical compounds it contains change structure and become poisonous (Walker 1984).

The brown "fuzz" on the back of young leaves can be licked and gives a "buzz" (Norman Hallendy, personal communication, 2005).

Ecology and habitat. Substrates: imperfectly drained moist areas, seepage slopes; acidic. Moss-lichen heath on sunny cliffs and ledges (Porsild 1957). Common in most parts of the south; local towards the northern limit of its range. It grows chiefly in dry, places that are covered by snow in winter but not drifted over so deeply that the last snow melting reduces the growing season. It is characteristic of the sides of mounds and the upper levels of the banks of streams. Sometimes it is dominant over considerable areas and often found adjacent to marshes.

North American distribution. Alaska, Yukon, Northwest Territories Islands, continental Northwest Territories, Nunavut Islands, continental Nunavut, northern Quebec, Labrador. Range in the Canadian Arctic Archipelago limited. Uncommon (but common where it occurs). Low Arctic. Arctic islands: Baffin, Victoria, Southampton.

Northern hemisphere distribution. North American, or Siberian. Yamal–Gydan, Taimyr – Severnaya Zemlya, Anabar–Olenyok, Kharaulakh, Yana–Kolyma, West Chukotka, Wrangel Island, South Chukotka, East Chukotka, West Alaska, North Alaska – Yukon, Central Canada, Labrador – Hudson Bay, Ellesmere Land – Peary Land, West Greenland.

General notes. Ledum is now included within Rhododendron (Kron and Judd 1990). For Labrador Tea, however, we are using the Ledum name because the combination has not yet been published under Rhododendron. Wallace (1992) published the subspecific combination with 'subarcticum', based on Harmaja's Rhododendron subarcticum. However, the name 'decumbens' has priority at subspecies level for this taxon, and therefore must be applied for this subspecies within Rhododendron tomentosum (Elven, personal communication, 2005).

Polunin (1940) stated that Labrador Tea varies little within the Arctic Archipelago except in luxuriance. The plants are generally prostrate and have small leaves, but sometimes grow to 20 cm high, with stems 0.6 cm thick and much broader leaves. The plant seems always to flower and generally to set fruit in abundance, even in its most northerly localities. Whether or not the species regularly sets seed has not been established from specimens in the herbarium at the Canadian Museum of Nature.

Savile (1969) considered the interrelationships of "Ledum" species and their rust parasites and found that the rust, Chrysomyxa ledi var. ledi, on Ledum palustre subsp. decumbens is morphologically distinct from C. ledi var. groenlandici, which occurs on Ledum groenlandicum Oeder, and suggested that this supports a species-level distinction between the two "Ledum" taxa.

In a study of the germination ecology of L. palustre subsp. decumbens and L. groenlandicum, Karlin and Bliss (1983) concluded that although the taxa are closely related, they had significantly different rates of germination. They found 94.3% of the total germination occurred within 12 days for 1-month-old seeds of L. palustre subsp. decumbens, while the corresponding value for R. groenlandicum was 36.4%. Both species were found to require light in order for the seeds to germinate, although the germination of L. groenlandicum was reduced in far-red rich light regimes, while that of L. palustre subsp. decumbens was not.

Kudo (1995) studied the leaf traits and shoot performance of L. palustre subsp. decumbens in accordance with latitudinal change. He found that at the Arctic sites this species produced leaves having longer life spans, higher nitrogen concentration, and smaller size and specific leaf area when compared with leaves at the temperate mountain site. Although current leaf number and annual shoot growth were smaller, leaf dry mass per stem was larger at the arctic site than at the temperate one. At a taiga site, those traits were within the range of the other two sites, with the exception of leaf size and total leaf number per stem, which was largest at the taiga site. Leaf life span was negatively correlated to specific leaf area and annual leaf number per stem and positively correlated to leaf nitrogen concentration. Thus, with increasing latitude, L. palustre subsp. decumbens produced fewer but more costly leaves and retained them for longer. Kudo (1995) suggested that old leaves might have a resource storage function supporting new leaf production.

Illustrations. • Habitat. Dominant flowering plant with lichens growing beside stream near the end of the runway. Plants are much branched, with ascending and prostrate stems. Nunavut, Baffin Island, Iqaluit. 22 July, 1982. J.M. Gillett 18995. CAN. • Close-up of plants. Plants with white umbellate inflorescences. Nunavut, Baffin Island, Soper River Valley. July, 2002. Aiken. No voucher. • Plant habit. Flowering plants with umbels of several small flowers with white petals. Large leaves and reddish (male) flowers in picture belong to Rubus chamaemorus (Rosaceae). Nunavut, Baffin Island, Iqaluit. 22 July, 1982. J.M. Gillett 18995. CAN. • Early season leaf bud. Leaf bud early spring. Note previous season's leaves reflexed against the stem and the dark colour they have been over winter. Nunavut, Baffin Island, Iqaluit. Phorograph Carolyn Mallory 2003. No voucher. • Close-up of growing tip. Growing tip with a dense cluster of leaves covered with brown deciduous hairs. Note the adaxial surfaces of the leaves are curled under leaving a strip of the brown hairs on the abaxial surface visible. Aiken 2002. No voucher. • Close-up of leaf. Leaf detached to show green revolute margins and dark brown hairs on the adaxial surface. 2003. No voucher. Photograph Carolyn Mallory. • Surface view of inflorescence in bud. Cluster of flower buds in a developing umbellate inflorescence. • Side view of umbel. Flower buds developing in the axils of brown scale-like leaves that are shed as the buds expand. Aiken 2002. No voucher. • Close-up of inflorescences. Plants with clusters of flower buds that are cream and tipped with red. Note the blooming flowers borne in umbels. Nunavut, Baffin Island, Iqaluit. 22 July, 1982. J.M.Gillett 18995. CAN. • Close-up of flowers. Flowers with five free petals (free petals are unusual in this family), 10 anthers arranged in two whorls, one is opposite and the other is alternate with the petals. There is a single, long, slender style with a capitate stigma. Nunavut, Baffin Island, Iqaluit. 22 July, 1982. J.M. Gillett 18995. CAN. • Close-up of flowers. Free and fused petals in the same family. Ledum has white flowers with free, overlapping petals. Compare with the bell-shaped fused petals from the lower flowers of the cranberry plant. Photo by Lynn Gillespie. • Pink flowers. Petals with pink tips, open anthers, and a superior gynoecium at the base of a stout style, which has a capitate stigma. Aiken 2002. No voucher. • Close-up of pinkish flower. Most pinkish colouration is on the undersurface of the five free petals. Ten anthers, a superior ovary covered in small hairs, and below it a glabrous, olive green nectary zone. Note thick style that holds the top of the capsule together when it opens and a flat, plate-like stigma. Nunavut, Baffin Island, Apex. 24 July, 2005. Photograph by Kathy Thornhill. No voucher. • Habitat: plants in fruit. Brownish remains of faded petals are clinging to developing capsules. The bluish green leaves of the Ledum are 6–15 mm long, and contrast with the lime green, smaller leaves 2–6 mm long of crowberry (Empetrum nigrum). Nunavut, Baffin Island, Iqaluit. Aiken 97–060. CAN. Scale bar in cm. • Close-up of young fruit. Early fruit development. Remains of petals still cling at the base of the immature green or reddish fruit, and the red styles persist. Nunavut, Baffin Island, Iqaluit. Aiken 97–060. CAN. • Close-up of capsules. Capsules that have opened from the receptacle splitting into the 5 capsule segments and still attached at the apex to the axis of the placentation and the style with the remains of the stigmas on top. LeBlanc 2004. No voucher. • Arctic Island Distribution.

This publication is available on the internet (posted May 2011) and on CD-ROM (published in 2007). These versions are identical in content, except that the errata page for CD-ROM is accessible on the main index page of the web version.

Recommended citation for the web-based version of this publication: Aiken, S.G., Dallwitz, M.J., Consaul, L.L., McJannet, C.L., Boles, R.L., Argus, G.W., Gillett, J.M., Scott, P.J., Elven, R., LeBlanc, M.C., Gillespie, L.J., Brysting, A.K., Solstad, H., and Harris, J.G. 2007. Flora of the Canadian Arctic Archipelago: Descriptions, Illustrations, Identification, and Information Retrieval. NRC Research Press, National Research Council of Canada, Ottawa. http://nature.ca/aaflora/data, accessed on DATE.

Recommended citation for the CD-ROM version of this publication: Aiken, S.G., Dallwitz, M.J., Consaul, L.L., McJannet, C.L., Boles, R.L., Argus, G.W., Gillett, J.M., Scott, P.J., Elven, R., LeBlanc, M.C., Gillespie, L.J., Brysting, A.K., Solstad, H., and Harris, J.G. 2007. Flora of the Canadian Arctic Archipelago: Descriptions, Illustrations, Identification, and Information Retrieval. [CD-ROM] NRC Research Press, National Research Council of Canada, Ottawa.