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

Chamerion angustifolium (L.) Holub

English: Yukon Fireweed,

French: Épilobe à feuilles étroites,

Inuktitut: Naparutaujuq, tiirluk.

Onagraceae, Fireweed family.

Published in Folia Geobot. Phytotax. 7: 86. 1972.

Synonymy. Epilobium angustifolium L., Sp. Pl. 347. 1753.

Chamaenerion angustifolium (L.) Scop. nom. illegit., Fl. Carniol., ed. 2, 1: 271. 1772.

Chamaenerion Gray, nom. illeg., Nat. Arr. Brit. Pl. 2: 559. 1821.

Vegetative morphology. Plants 20–40 cm high (to 100 cm tall on continental North America); perennial herbs. Only fibrous roots present. Ground level or underground stems horizontal; rhizomatous; elongate (in old plants), or compact; 4–6 mm wide. Aerial stems developed; erect (stiffly). Aerial stem trichomes spreading, or retrorse (if applicable). Leaves present; distributed along the stems; alternate (usually), or opposite; dying annually and non-persistent. Petioles present, or absent; 0–2 mm long (if applicable); glabrous. Leaf blade bases obtuse, or cuneate. Leaves not grass-like. Blades 25–75(–90) mm long, 2–15(–18) mm wide, spreading, linear or lanceolate, flat, veins pinnate. Blade adaxial surface glabrous or glabrescent, hairs simple. Blade abaxial surface hairy, hairs puberulent, hairs sparse, hairs white, hairs curved. Blade margins entire, glabrous; apices acuminate.

Reproductive morphology. Flowering stems two or more per plant; with leaves. Flowering stems hairy. Flowering stems puberulent (if applicable). Flowering stem hairs simple; shorter than the diameter of the flowering stem; white or translucent. Inflorescences racemose; diffuse; elongating as the fruit matures. Pedicels present; with non-glandular hairs (densely tomentose). Flowers per inflorescence 8–20 (to 80 in the Yukon); medium-sized, or large. Sepals conventional; 4; free; 1.5–2.5 mm long; 4–15 mm wide; purple. Calyx hairy. Calyx hairs pubescent (conspicuously so on the buds); non-glandular; white or translucent. Petals conventional; free; 4; white (rarely), or pink, or purple (paler than the sepals, fading bluish purple); spatulate; unlobed; 10–20 mm long; 10–18 mm wide (3 mm wide at the base). Stamens 8; stamen filaments glabrous. Anthers purple; 1.7–2.2 mm long. Nectaries present (but not very conspicuous). Ovary inferior; carpels 4; syncarpous. Ovaries hairy; tomentose. Ovary hairs very dense; white. Styles 1; 8–12 mm long; straight; basal portion with hairs at the base. Stigmas per ovary 4. Stigma lobes 4–5 mm long. Placentation axile. Ovules per ovary very numerous. Fruit stalked; stalk 5–10 mm long; dry; a capsule; elongate-cylindrical; straw-coloured (or greyish); 30–50 mm long; 1–2.5 mm wide; hairy; surface appearing veinless; not distinctly flattened; dehiscent; splitting to the base into separate segments; teeth 4. Seeds numerous (as many as 500 per fruit); 0.8–1.4 mm long; yellowish; surfaces smooth (apex with silky tufts of hairs to 10 mm long).

Chromosome information. 2n = 36.

2n = 36. Löve and Löve (1948, northern Europe; 1956, Iceland; 1982a, Arctic Canada); Böcher and Larsen (1950, Greenland); Sorsa (1962, Finland); Lövkvist, in Weimarck (1963, Sweden); Mosquin (1963, 1966, Canada; 1967, USA, numerous counts); Laane (1965, 1969b, Norway); Knaben and Engelskjøn (1967, Norway); Johnson and Packer (1968, northwestern Alaska); Taylor and Mulligan (1968, western Canada); Sokolovskaya (1970, northeastern Russia); Zhukova et al. (1977, northeastern Asia); Dawe and Murray, in Löve (1981a, western Alaska); Uotila and Pellinen (1985, Finland); Dalgaard (1989, western Greenland); Lövkvist and Hultgård (1999, southern Sweden). Very numerous more southern counts.

Ploidy levels recorded 4x.

Indigenous knowledge. Anderson (1939) noted that in Alaska young shoots of this fireweed were gathered and boiled, usually mixed with Rumex. If bacon was added, the dish was said to be delicious.

People have used fireweed as food. The young shoots have been consumed as greens, the leaves used to make tea, the petals made into jelly, and the roots eaten as a vegetable (Small and Catling 1999).

Andre and Fehr (2000) reported that Gwich'in people know that the whole plants can be boiled as a medicine and the liquid rubbed on the skin for rashes. A poultice is made from the leaves and applied to burns, bee stings, aches, and swelling caused by arthritis. The pink flowers are edible and can be mixed in with jello and salads. The new shoots can be cooked like asparagus, chopped and eaten as greens, or mixed with salads.

Ecology and habitat. Substrates: cliffs (gull cliffs and ledges opposite Pangnirtung); dry; rocks, gravel. Occasional on southfacing screes in the Arctic islands.

Mosquin (1966), referring to his experiences in North America, noted that populations of this species grow in a remarkably diverse range of environments, occurring from sea level in central and northern regions to 13,000 feet (4000 m) in the mountains of western North America and to 16,000 ft (over 5000 m) in the Himalayas. Populations may be extremely common in open and semi-open habitats of the boreal forest. For example, during the period of maximum flowering over large areas of Alaska, the Yukon, and Quebec (and presumably boreal Europe) plants tend to be so common as to impart a pink colour to large areas of countryside (Shacklette 1964). In the Arctic, individuals are often found in sheltered places in the tundra. In the mountains, they occur in a wide variety of sites: cut and burnt over lands, road cuts, rocky and scree slopes, beside stream, and in alpine meadows. This is particularly true in the northern Yukon.

Breeding Habit. Plants of this species are protandrous and self-incompatible. Pollen is shed soon after anthesis, but the stigma remains closed and strongly reflexed away from the anthers for two or three days. During dehiscence, the pollen is attached to the anther by long threads. Pollination is accomplished by various Hymenoptera, which visit the flowers actively and occasionally by the movement of the stems by wind. After most of the pollen is shed, the stigma comes forward while the anthers become deflexed. The stigma opens and may then be pollinated. Nectar is produced continuously beginning about one day after anthesis and ending with the abscission of the floral parts. In plants growing under greenhouse conditions in the absence of wind or insects, automatic self-pollination nearly always failed to occur, and such plants retained their flowers for a week or longer.

Salisbury (1961) estimated that each fruiting capsule contains 300–500 seeds and each flowering stem about 80,000, and far greater numbers are not exceptional. Under greenhouse conditions plants readily grow from seed to fruit in about 60 days. Böcher (1962) observed that populations in Greenland are sterile, and Mosquin (1966) claimed that plants at the limits of the distribution range in northern Canada are often unable to reproduce. He suggested that this is undoubtedly very often environmentally induced by the extreme climate. He also claimed there was no evidence that sterility is caused by hybridisation of this species with C. angustifolium, as suggested by Forsaith (1916).

North American distribution. Alaska, Yukon, continental Northwest Territories, Nunavut Islands, continental Nunavut, northern Quebec, Labrador. Range in the Canadian Arctic Archipelago limited (widespread on continental North America). Rare. Alpine (temperate-boreal), Low Arctic (rarely). Arctic islands: Baffin (southeast).

Northern hemisphere distribution. Circumpolar, or circumboreal. Northern Iceland, Northern Fennoscandian, Kanin–Pechora, Polar Ural – Novaya Zemlya, Yamal–Gydan, Taimyr – Severnaya Zemlya, Kharaulakh, West Chukotka, South Chukotka, East Chukotka, West Alaska, North Alaska – Yukon, Central Canada, Labrador – Hudson Bay, West Greenland, East Greenland.

Economic uses. Beekeepers have found this species to be one of the best sources of nectar (Sladen 1920, Arant 1935, Pellett 1947). Nectar flow in wild populations shows a remarkable variation, depending on the locality and season and is apparently environmentally controlled.

General notes. The Yukon territorial flower.

Mosquin (1966) studied the taxonomy (of what he called Epilobium angustifolium) because he wished to establish the way in which chromosomal discontinuity correlated with morphological discontinuities after three chromosomal races with n =18, 36, and 54 had been discovered (Mulligan 1957 and Mosquin 1963). Mosquin recognised subspecies angustifolium, n = 18 and 54, and subspecies circumvagum Mosquin, n = 36, the later based on Chamaenerion angustifolium var. platyphyllum Daniels. The best characters for distinguishing the taxa are the pubescence, or lack of it, on the abaxial leaf midribs, the leaf width and length, whether the pollen is triporate, or a mixture of pore sizes, and the diameter of the pollen. Mosquin (1966) mapped the distribution of 95 chromosome records; a map that indicates that plants with 2n = 36 are not found as far north as 60°N.

Mosquin (1966) stated that white-flowered forms are generally most common in 2n = 18 plants, less common in 2n = 36 plants, and apparently unknown among 2n = 54 plants.

Mosquin and Small (1971, p. 680, 681) considered that C. angustifolium and C. latifolium represent an example of parallel evolution and that "although the two species are closely related, evidence indicates that they are isolated by ecological and genetic barriers. [They admitted that] F1 hybrids have been collected from transitional habitats (Böcher 1962) [but noted that hybrids are] extremely infrequent in view of the occurrence of widespread areas of sympatry... Attempts to cross the two species have given variable results (Pugsley 1960, Mosquin, unpubl.) but generally revealed strong barriers to F1 seed production coupled with marked F1 pollen sterility. While these barriers were not considered sufficiently well developed to have prevented introgression between the two species, [Mosquin and Small (1971) stated that] there iss no indication of this in the polyploids, which closely resemble their diploid progenitors, and do not possess characters attributable to introgression from their sister species.

Evidence for parallelism comes from five observations:

(1) Both species occupy comparably widespread ranges in the northern hemisphere...

(2) In each species diploids occupy the more northern and/or alpine areas, while polyploids occur in more southern and/or warmer regions.

(3) In each species autopolyploidy has been the mechanism of polyploidisation.

(4) Each species has retained the capacity to form high levels of quadrivalents at meiosis, unlike many other autopolyploids (Morrison and Rajhathy 1960).

(5) Within each species the diploids very closely resemble the polyploids."

Mosquin and Small (1971) suggested "the evolution of polyploidy has been accompanied by a common morphological change, namely an increase in frequency of extra pores in the pollen grains." (p. 682).

Small and Catling (1999) noted that despite the ‘weed’ in fireweed, this species is not usually a significant weed in Canada, although it is a weed in Europe. Potential problems for forest managers may exist, since C. angustifolium seedlings can compete with conifer seedlings in revegetating burned land, and C. angustifolium serves as the alternative host of conifer rusts. Fireweed has also been observed to be a weed of some vegetable crops in northern regions.

Inbreeding depression, which is reduced fitness following self-fertilisation, is extreme in fireweed, making cross-pollination very important. Individual flowers mature their pollen before the stigma is receptive, which prevents selfing. Bees, bumblebees, moths, and butterflies are important pollinators of fireweed. They characteristically move from the bottom towards the top of the flowering stem. The insects visit the lower flowers, which have opened first, have already shed their pollen, and have receptive stigmas. They then move up the inflorescence where they acquire pollen from the upper flowers, which have not yet exposed their stigmas (Small and Catling 1999, Galen and Plowright 1985, Husband and Schemske 1997).

A fruit of fireweed can contain as many as 500 seeds, and a single plant may produce as many as 80,000 seeds per year (Small and Catling 1999). The plumose seeds can be carried by wind for hundreds of kilometres (Solbreack and Andersson 1987). A Swedish study revealed that up to half of the seed produced disperses over the landscape more than 100 m above the ground. Humidity expands the diameter of the seed hairs, decreasing loft, an adaptation that tends to deposit the seeds in humid areas and during wet periods. The seeds are non-dormant and short-lived, rarely remaining viable for more than 3 years and generally germinating as soon as a suitable site is found.

Although seeds account for the remarkable ability of fireweed to colonise new areas, once a seed germinates, vegetative reproduction by rhizomes becomes more important than sexual reproduction. Fragmentation of the rhizomes stimulates production of shoots, contributing to the reputation of fireweed as a hard-to-eradicate weed. Most of the rhizomes occur in the top 5 cm of mineral soils, and this underground portion can survive relatively intense fires. The aboveground shoots of older plants are killed by frost, but the plants overwinter as rhizomes (Small and Catling 1999). Fireweed sprouted quickly from surviving rhizomes, following the volcanic eruption of Mount St. Helens, Washington, in 1980. One year after the explosion, 81% of all seedlings present were from fireweed.

Fireweed is not considered toxic. Compounds, such as an unusual flavonoid myricetin 3-O-ß-D-glucuronide, with strong healing antiseptic and anti-inflammatory effects, have been found in the foliage. This active principle reaches its maximum concentration during and shortly after the plants flower (Ducrey et al. 1995). In Norway we sometimes (not very often) make a very nice and refreshing drink from it, boiling fresh leaves. There has been no rumour of poisonous effects at all in Europe; it is rather seen as a useful (but slightly noxious weedy) plant (Elven, personal communication, 2005).

It has been suggested that mutations from the radiation near uranium deposits results in a relatively high frequency of white-flowered variants of fireweed, and that this phenomenon can be used to find uranium (Shacklette 1964).

This species was found to be an early coloniser of oil spills in Alaska (Kershaw and Kershaw 1986). It is an early and efficient coloniser almost everywhere.

Porsild annotated a specimen (CAN 223779) that was collected from the Gull cliffs opposite Pangnirtung on 15 August 1953 by V.C. Wynne-Edwards as Epilobium angustifolium L. × E. latifolium L. On the label is the note, "both parent species and every gradation of hybrid, in profusion on manured ground beneath the gull cliff opposite Pangnirtung Post. C. latifolium was already finished flowering. E. angustifolium only in bud, and the hybrids make a great show of colour." Peter C. Hoch, Missouri Botanical Garden, annotated the specimen in 1979 as E. angustifolium subsp. angustifolium. The observed difference in flowering time would make hybridisation less likely.

Illustrations. • Habitat. Relatively short plants about 25 cm high, with few flowers, growing in dry gravel, and with little organic content. Manitoba, Churchill. Aiken and Brysting 01–003. • Habitat. Taller plants, with many more flowers, growing in shrubby tundra, with more organic content in the soil and probably more moisture than in previous picture. Manitoba, Churchill. Aiken and Brysting 01–003. • Habit. Adjacent plants that have flowers with pink and other flowers with white petals. Manitoba, Churchill, Fort Prince of Wales. 27 July, 2006. Aiken. No voucher. • Close-up of rhizome. Rhizome of a large and vigorous plant growing on river flats along Dempster Rd. Yukon, Ogilvie Mountains. 30 July, 1966. R.T. Porsild 371. CAN 303679. • Close-up of inflorescence. Top of racemose inflorescence showing open flowers at the base and developing buds at the top. Each flower has an inferior ovary at the top of a pedicel. Manitoba, Churchill. Aiken and Brysting 01–003. • Close-up of inforescence. Inflorescence with flowers at different stages of maturity. Manitoba, Churchill. Aiken and Brysting 01–003. CAN. • Close-up of flower. Close-up of a pre-anthesis flower with four thin red-pink sepals, four broad purple-pink petals, and eight developing stamens with red anthers and white filaments. The style is not visible because it does not elongate until after the pollen is shed and the anthers wither. Manitoba, Churchill. Aiken and Brysting 01–003. • Close-up of flower. Flower in which the first whorl of four anthers is shedding pollen, and the second whorl of anthers is still pre-anthesis. Note the narrow base of the petals. Manitoba, Churchill. Aiken and Brysting 01–003. • Close-up of flower. Flowers with four free linear-lanceolate, reddish pink sepals, obovate free petals, old anthers that have shriveled, and fully elongated styles with four receptive stigma lobes. Manitoba, Churchill. Aiken and Brysting 01–003. • 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.