Flora of the Canadian Arctic Archipelago
Inuktitut: Avalaqiat, napaaqturalaat.
Betulaceae, Birch family.
Published in Sp. Pl. 982. 1753.
Vegetative morphology. Plants 10–30(–50) cm high; shrubs; forming colonies by layering; glandular viscid. Aerial stems erect, or decumbent, or prostrate. Branches grey-brown, or red-brown, or brownish; covered with numerous, raised, large resinous wart-like glands, or covered with few inconspicuous sessile glands; glabrous, or glabrescent, or hairy. Branchlets grey-brown, or red-brown; glabrous, or hairy. Leaves distributed along the stems; alternate; dying annually and non-persistent. Petioles 0.5–6(–10) mm long; glabrous, or hairy. Juvenile leaves glabrous. Leaf blade bases obtuse, or cuneate, or rounded. Blades 5–20(–40) mm long, 3.5–15(–40) mm wide, circular or ovate or obovate, flat, veins pinnate. Blade adaxial surface fresh green or shiny, glabrous. Blade abaxial surface glabrous or hairy. Blades not lobed (interpreted as deeply crenate). Blade margins crenate or dentate, with teeth toward the apex, with teeth per cm 2–8; apices obtuse, or rounded.
Reproductive morphology. Plants monoecious. Flowering stems with leaves (on short shoots). Inflorescences catkins; dense; cylindrical. Pedicels absent. Catkins flowering as leaves emerge. Female catkins 5–15(–25) mm long; 3–12 mm wide; stout, or sub-globose; peduncles 1–3 mm long; borne on a flowering branchlet. Floral bracts green (or a calyx in the male flowers); 0.5–2(–2.5) mm long; 0.8–2 mm wide; apices divided into 3-lobes. Flowers unisexual. Staminate flowers inconspicuous (staminate catkins mostly terminal on branchlets, rarely preserved). Sepals absent (female flowers), or conventional (male flowers). Petals absent. Stamens present (male flowers), or absent (female flowers); (1–)2–3(–4). Ovary inferior; carpels 2; syncarpous. Styles 2; free. Ovules per ovary 1. Fruit dry; a samara. Seeds 1.
Ecology and habitat. Substrates: tundra.
North American distribution. Range in the Canadian Arctic Archipelago limited. Low Arctic.
General notes. Andrews et al. (1980) provided a distribution map for dwarf birches occurring in the region from Frobisher Bay northwards to Cumberland Peninsula and noted that the shrubs are restricted to favourable habitats, which at the northern limit of the species (67°40'N) are found on south-facing slopes above the immediate local cooling influence of the sea. Pollen studies within the zone of scattered dwarf birch indicated that pollen dispersal from these low, prostrate shrubs is minimal. Samples of moss collected beneath the bushes have 5–36% pollen; whereas sites no more than 50 m away from Betula shrubs have percentages of less than 2%. Andrews et al. (1980) suggested that their data will be useful in considering the Holocene and Pleistocene histories of these Low Arctic shrubs in the eastern Canadian Arctic.
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..