Flora of the Canadian Arctic Archipelago

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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

Onagraceae A.L. de Jussieu

English: Fireweed family.

Onagraceae, Fireweed family.

Vegetative morphology. Plants (2–)5–30(–40) cm high (to 100 cm tall on continental North America); perennial herbs. Only fibrous roots present. Ground level or underground stems horizontal, or absent (if applicable); rhizomatous (C. angustifolium); elongate, or compact; 2–9 mm wide. Ground level or underground stems scales present (in terminal buds on the rhizomes, E. palustris). Caudex present, or absent. Aerial stems developed; erect, or ascending, or decumbent. Aerial stem trichomes appressed, or spreading, or retrorse. Leaves distributed along the stems; alternate, or opposite (or pseudo-opposite); not distinctly distichous; dying annually and non-persistent. Petioles present, or absent; 0–2 mm long (if applicable); glabrous, or hairy, or glabrescent. Leaf blades simple. Leaf blade bases truncate, or obtuse, or cuneate, or attenuate. Blades (4–)10–60(–90) mm long, 1–15(–22) mm wide, spreading, linear or oblong or lanceolate or ovate or obovate, flat, veins pinnate or appearing single-veined. Blade adaxial surface glabrous or glabrescent, hairs simple. Blade abaxial surface glabrous or glabrescent or hairy, hairs puberulent (if applicable), hairs sparse or moderately dense or very dense, hairs white, hairs curved (if applicable). Blade margins entire or dentate (or shallowly sinuate, repand dentate), glabrous; apices acuminate, or acute, or obtuse, or rounded.

Reproductive morphology. Flowering stems with leaves. Flowering stems hairy. Flowering stems puberulent, or pubescent. Flowering stem hairs simple; shorter than the diameter of the flowering stem; white or translucent. Flowers solitary, or in inflorescences. Inflorescences racemose (if applicable); terminal, or lateral; diffuse; elongating as the fruit matures. Pedicels present; with non-glandular hairs (usually). Flowers per inflorescence 1–8(–20) (or 40 further south); small, or medium-sized, or large; radially symmetrical (actinomorphic). Sepals conventional; 4; free; 0.5–5.5 mm long; 3–18 mm wide; green and red, or purple. Calyx without sessile glands; glabrous, or hairy. Calyx hairs puberulent, or pubescent; non-glandular; white or translucent. Petals conventional; free; 4; white, or pink, or purple; without contrasting markings; obovate, or lanceolate, or spatulate; unlobed, or slightly lobed or undulating; 4–25 mm long; 1–22 mm wide. Stamens 8; stamen filaments glabrous. Anthers 0.3–2.2 mm long. Nectaries present (sometimes inconspicuous). Ovary inferior; carpels 4; syncarpous. Ovaries glabrous, or hairy; puberulent, or pubescent, or villous, or tomentose. Ovary hairs sparse, or very dense; white. Styles 1; 2–12 mm long; straight; basal portion smooth, or with hairs at the base. Stigmas per ovary 4. Stigma lobes 2–5 mm long. Placentation axile. Ovules per ovary numerous and tiny. Fruit stalked; stalk 5–40 mm long; dry; a capsule; elongate-cylindrical; brown, or red, or purple, or straw-coloured; 20–70 mm long; 1–3.5 mm wide; hairy, or glabrescent; surface appearing veinless; not distinctly flattened; dehiscent; splitting to the base into separate segments; teeth 4–5. Seeds numerous; 0.8–2 mm long; black, or brown, or yellowish; surfaces smooth, ridged.

General notes. Orel (1977) discussed the taxonomic rank of the genera Epilobium and Chamaenerion in the Family Onagraceae on the basis of investigating the pollen and the pore openings.

The distribution of the Onagraceae in Greenland was mapped by Fredskild (1985).

Baum et al. (1994) published a phylogenetic analysis of Epilobium based on sequences of the ITS regions and the 5.8S cistron of nuclear ribosomal DNA. They found that section Chamaenerion (which includes our Chamerion [Epilobium] angustifolium and C. [E.] latifolium) was sister to the rest of the genus. Holub (1972) had previously argued that the nine species in this group were easily morphologically distinguishable and supported treating it as a separate genus. He presented evidence that the name Chamaenerion (although long used for this group) was illegitimate, and he published the new combinations with Chamerion.

Levin et al. (2003) discussed family-level relationship of Onagraceae based on chloroplast rbcl and NDHF data.


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.

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