Betulaceae S.F. Gray
Birch Family.
Betulaceae, birch family.
Vegetative morphology. Plants shrubs; 10–30(–50) cm high; woody shrubs with matted prostrate or ascending stems. Aerial stems erect, or decumbent, or prostrate; covered with numerous, raised, large resinous wart-like glands, or covered with few inconspicuous sessile glands; glabrous, or densely hairy. Branches grey-brown, or red-brown, or brownish; glabrous, or glabrescent, or hairy. Branchlets grey-brown, or red-brown; glabrous, or hairy. Leaves distributed along the stems; alternate; existing for a single season or less. Petioles 0.5–6(–10) mm long; glabrous, or hairy. Leaf blade bases obtuse, or acute, or rounded. Juvenile leaves glabrous. Blades 5–20(–40) mm long; 3.5–15(–50) mm wide. Blades circular, or ovate, or obovate; veins pinnate. Blades secondary veins arising along midrib. Blades adaxial surface glabrous. Blades abaxial surface glabrous, or hairy. Blade margins not lobed (considered deeply crenate). Blade margins crenate, or dentate; with teeth toward the apex; with teeth per cm 2–8. Leaf apices obtuse, or rounded.
Reproductive morphology. Plants monoecious. Flowering stems present. Flowering stems with leaves (on short shoots). Inflorescence a catkin; dense; cylindrical. Pedicels absent. Catkins flowering with the opening of leaf buds. Female catkins densely flowered; 5–15(–25) mm long; 3–12 mm wide; stout, or subglobose; peduncles 1–3 mm long; borne on a flowering branchlet. Staminate flowers inconspicuous (staminate catkins mostly terminal on branchlets, rarely preserved). Floral bracts green; widest toward tip; 0.5–2(–2.5) mm long; 0.8–2 mm wide; apex obtuse. Perianth absent. Flowers unisexual. Gynoecia inferior. Carpels syncarpous; 2. Styles 2; free. Ovules 1. Fruit dry; a samara. Fruit information not found. Seeds 1.
Distribution. Northern hemisphere distribution: Greenland, Canada. Low arctic. Range in the Canadian Arctic Archipelago limited.
Ecology and habitat. Substrates: tundra.
Indigenous knowledge. Inuktutuk names: avalaqiat, napaaqturalaat.
Notes. When Hamet-Aht ( ) proposed this name combination he noted that it was first described at variety level (not as a form as often cited) by Ruprecht (1845) from arctic Russia. Trautvetter (1871, p. 74; not Ruprecht as reported by Porsild (1932, p. 72) considered it a synonym of Pyrethrum ambigum described by Ledebour (1833, p. 118) from the Altai Mountains. Thereafter many later authors have applied the epithet ambigum to this taxon. Hamet-Aht ( ) had seen the types of both Ruprecht and Trautvetter and noted that although Ruprecht's type specimen is very poor, a comparison of other material from northenmost Russia and the Altai material showed so many differences that he could not regard them as identical. The main differences noted are the bracts are narrower, only slightly triangular, and the leaf segments are shorter and narrower in the Altia specimens than in those from northern Russia. Ecologically T. maritimum Supsp. phaeocephalum is both a seashore and an ruderal plant.
Illustrations. • Betulaceae: birch family. Woody plants with small flowers borne in bisexual catkins.
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).
