Epilobium palustre L.
Onagraceae, fireweed family.
Sp. Pl. 1: 348. 1753.
Vegetative morphology. Plants perennial herbs; (10–)15–25(–40) cm high; with simple or branched stems, lanceolate leaves, and small, pink or whitish flowers. Caudex absent. Ground-level or under-ground stems horizontal; rhizomatous; elongate (and filiform, often not present on herbarium specimens). Scales present (in terminal buds on the rhizomes). Aerial stems erect; not conspicuously jointed; sparsely hairy (at the base), or densely hairy (at the apex); stem hairs appressed, or reflexed (so that they lie appressed). Leaves distributed along the stems; opposite (near the roots and in smaller plants), or alternate (near the inflorescence in taller plants); simple; existing for a single season or less. Petioles present, or absent (leaves subsessile); 0.5–2 mm long; hairy, or glabrescent; puberulent (if applicable). Petioles hairs appressed; wavy (sparse). Leaf blade bases attenuate. Blades 10–30(–40) mm long; (2–)3–5(–9) mm wide. Blades spreading; linear, or lanceolate; flat; appearing single-veined. Blades adaxial surface glabrous. Blades abaxial surface glabrous (mostly, sometimes with a few hairs on the midvein). Blade margins entire. Leaf apices acuminate (usually), or acute.
Reproductive morphology. Flowering stems present. Flowering stems with leaves; hairy. Flowering stem hairs pubescent; simple; shorter than the diameter of the flowering stem; white or translucent. Inflorescence racemose (flowers in the axils of very well-developed leaves); diffuse. Pedicels with non-glandular hairs. Flowers per inflorescence (1–)2–6; small, less than 5 mm in diameter or length, or medium-sized, 5–15 mm in diameter or length, or large, more than 15 mm in diameter or length. Perianth present. Calyx sepals 4; free (valvate in bud and appearing fused at that stage, gradually splitting to the base as the flower opens); 3.5–5 mm long; 1.1–1.3 mm wide. Calyx green; glabrous. Petals free; 4; white, or pink (fading bluish); lanceolate; shallowly lobed (with a distinct notch, approximately 25% of the length of the petal); 4.5–6 mm long; 1–1.5 mm wide. Stamens 8; filaments glabrous. Anthers 0.4–0.6 mm long. Nectaries present (rudimentary). Gynoecia inferior. Carpels syncarpous; 4. Ovaries hairy; villous. Ovary hairs dense; white, or translucent. Styles 1; 2–4 mm long. Styles straight. Stigmas per style 1; broad-cylindrical (1–1.2 mm across). Placentation axile. Ovules numerous. Fruit stalked; stalk (15–)20–30 mm long. Fruit dry; a capsule; elongate-cylindrical; not distinctly flattened; dehiscent; splitting to the base into separate segments; teeth 5. Fruit (25–)30–50(–60) mm long; 1.2–1.5 mm wide; purple (when young), or brown (drab); hairy; surface appearing veinless. Seeds numerous; 1–1.2 mm long; black (with plumose tufts 7–8 mm long); with surfaces smooth.
Chromosome information. 2n = 36. Böcher (1938b northern Europe); Löve and Löve (1948 Iceland, 1956b Iceland, 1966b north eastern USA, 1982a central Canada); Lövkvist in Weimarck (1963 Sweden); Löve and Ritchie (1966 central Canada); Johnson and Packer (1968 northwestern Alaska ); Zhukova and Petrovsky (1976 western Chukotka); Zhukova et al. (1977a north eastern Asia); Krogulevich (1976 northern Siberia); Seavey and Raven (1977, 1977a); Zhukova (1982 north eastern Asia); Krasnikov and Schaulo (1990 Siberia). Several more southern counts. Ploidy levels recorded 4x.
Distribution. Northern hemisphere distribution: circumpolar; Greenland, Canada, United States, Eurasia. Alaska, Yukon, Continental Northwest Territories, Nunavut Islands, Continental Nunavut, Northern Québec. Low arctic. Range in the Canadian Arctic Archipelago limited. Arctic Islands: Southampton (single record from the Archipelago (CAN 583987)).
Ecology and habitat. Substrates: wet meadows, along streams, lake shores; imperfectly drained moist areas; acidic; rocks, gravel, sand, moss (muskeg); with high organic content (submerged organic over sandy loam (CAN 483132). Habitats: rocky lake shore near sand dunes (CAN 200186); Carex stans meadow (CAN 535486); closed depression in poorly drained organic soil (CAN 483133); Carex aquatilis-Comarum palustre marsh (CAN 483135); raised dry gravel mounds with Arctophila fulva and Cardamine pratensis (CAN 583987).
Notes. Bednara (1977 and 1978) described the development of the monosporic, tetranucleate embryo sac of E. palustre, and the embryology of the macrospore tetrad.
Illustrations. • Habitat. Small white dots between the markers are flowers of this dwarf species, growing on plants that were a wet sedge meadow, in the shelter of a Salix shrub. Nunavut, Rankin Inlet, Aiken and Brysting 01–056. CAN. 583958. • Habitat. Small white dots behind the markers are flowers of this dwarf species that were conspicuous against the green of a sedge meadow. Nunavut, Southampton Island, Coral Harbour, Aiken and Brysting 01–088. CAN 583987. The larger white dots are Eriophorum. • Close-up of plants. Small flowers with 4 white petals. Side view of the flowers shows pinkish-green sepals, op top of a swollen inferior ovary. . between the markers are flowers of this dwarf species, growing on plants that were a wet sedge meadow, in the shelter of a Salix shrub. Nunavut, Rankin Inlet, Aiken and Brysting 01–056. CAN. • Close-up of plant. Dwarf species that has a racemose inflorescence with three flowers borne on pedicels that arise in the axils of leaves. Note the long, swollen, inferior ovary, the pinkish brown sepals and the white petals. Aiken and Brysting 01–088. CAN 583987. • Close-up of flower. Note four narrow sepals that are green on the inner surface, reddish on the outer surface, and alternate with the four white lobed, ovate petals. These are wider at the base than the petals of our Chamerion species. There are 4 dehisced anthers opposite the sepals and an inner whorl of 4 post-anthesis anthers opposite the petals and close to the swollen stigma. Coral Harbour, Southampton Island, Nunavut, Aiken and Brysting 01–056. 30 July 2001. CAN 583987. • Close-up of flower. Side view of flower showing the characteristically hairy inferior ovary, and the pinkish green lanceolate sepals. These are alternate with the petals, and only half a petal is seen in this view, and the notch is not visible. Rankin Inlet, Nunavut, Aiken and Brysting 01–056. 27 July 2001, CAN 583958. • oneppas1.jpg. Herbarium specimens showing elongate, filiform, leafy ground-level stems (an example indicated by the red arrow), that is characteristic of this species. Aiken and Brysting 01–056. CAN 583958. • Arctic Island Distribution.
Cite this publication as: ‘S.G. Aiken, M.J. Dallwitz, L.L. Consaul, C.L. McJannet, L.J. Gillespie, R.L. Boles, G.W. Argus, J.M. Gillett, P.J. Scott, R. Elven, M.C. LeBlanc, A.K. Brysting and H. Solstad. 1999 onwards. Flora of the Canadian Arctic Archipelago: Descriptions, Illustrations, Identification, and Information Retrieval. Version: 29th April 2003. http://www.mun.ca/biology/delta/arcticf/’. Dallwitz (1980) and Dallwitz, Paine and Zurcher (1993, 1995, 2000) should also be cited (see References).
