Flora of the Canadian Arctic Archipelago
English: Dark brown sedge,
French: Carex brun foncé,
Inuktitut: Iviit, ivisuka, ivitsuskaka.
Cyperaceae, Sedge family.
Published in Beschr. Riedgräs. 106. 1801.
Type: Described from Austria: Kärnten. Holotype: HAL.
Synonymy. Carex ustulata Wahlenb. Wahlenb., Kongl. Vetensk. Acad. Nya Handl. 24: 156. 1803.
Vegetative morphology. Plants (6–)15–30 cm high (Arctic islands, to 60 cm high on continental North America); perennial herbs; caespitose; loosely tufted in several tufts. Only fibrous roots present. Roots pallid-brown. Ground level or underground stems horizontal; rhizomatous; compact. Ground level or underground stems scales present. Aerial stems decumbent. Leaves mainly basal; alternate; marcescent. Petioles absent. Sheaths present; persisting (breaking into fibres after the first year); not forming a conspicuous build-up at the base of the plant; brown; sheath collars absent. Ligules present. Leaves grass-like. Blades 20–130 mm long, 1.5–3.5 mm wide (Arctic islands), straight, linear, flat or revolute (glaucous), veins parallel. Blade adaxial surface glabrous. Blade abaxial surface glabrous. Blade margins scabrous (scaberulous at the tip); apices acuminate.
Reproductive morphology. Plants monoecious. Flowering stems triangular in cross section. Flowering stems conspicuously taller than the leaves; with leaves. Leaf or reduced bract subtending the base of the inflorescence present; reduced, or scale-like (often bristle pointed); shorter than the apex of the inflorescence; 10–20(–25) mm long (sheath cylindrical, mouth usually tinged dark purple); persistent; with sheath shorter than the blade. Inflorescences a raceme of spikes; 2–3.5 cm long (Arctic islands, to 8 cm long on continental North America); 20–30 mm wide. Pedicels glabrous (capillary, to 4 cm long on proximal spikes). Cladoprophylls present. Inflorescence multispicate. Inflorescence 2–4 spikes. Individual spike(s) erect (dwarf specimens), or pendent (lateral spikes pistillate 8–19 mm long × 4–7 mm wide). Terminal spike completely staminate, or staminate at the apex (club-shaped erect, 6–15 × 2–5 mm, rarely two spikes have staminate flowers). Floral scales as long as the perigynium in fruit; black; with margins and sometimes midvein paler in colour than the adjacent area of the scale; ovate, or lanceolate (bristle-tipped); 3.5–4.5 mm long; 0.7–1 mm wide; glabrous (minutely papillose, at least in the centre). Flowers unisexual. Staminate flowers conspicuous (usually). Perianth represented by a perigynium. Sepals modified (but not a pappus). Stamens present (staminate flowers), or absent (pistillate flowers); 3. Anthers 1.5–3.5 mm long. Ovary superior; carpels 3; syncarpous. Perigynia sessile. Styles 3; partially fused; slender, not extending beyond the beak. Stigmas per ovary 3. Placentation basal. Ovules per ovary 1. Fruit surrounded by a perigynium. Perigynia fused to the apex except for a small aperture through which the style protrudes; broadly ovate; 3–4.5 mm long; 2–2.5(–3) mm wide; erect or ascending; black; membranous; surface dull; papillose (minutely); appearing veinless; not keeled (scaberulous towards the apex); apices beaked with a long beak; apex deeply bidentate. Fruit sessile; dry; an achene; indehiscent. Achenes trigonous; not filling the upper part of the perigynia. Seeds 1.
Chromosome information. 2n = 36 (or 38 to 42).
2n = 36. Heilborn (1924, 1928, northern Europe);
2n = 40. Sørensen and Westergaard, in Löve and Löve (1948, Greenland); Jørgensen et al. (1958, Greenland); Dietrich (1964, 1967); Löve and Löve (1965); Löve and Ritchie (1966, northern Canada); Knaben and Engelskjøn (1967, southern and northern Norway);
2n = about 42. Hedberg (1967, northern Canada); Johnson and Packer (1968, northwestern Alaska); Zhukova (1969, northeastern Asia; 1980, southern Chukotka); Krogulevich (1976, northern Siberia); Löve (1981d, northern Canada); Malychev (1990).
Ecology and habitat. Substrates: wet meadows, hummocks, marshes, along streams, river terraces, lakeshores, tundra; imperfectly drained moist areas, seepage slopes; gravel, sand, silt, till (often on till plains), moss; with high organic content, peat (occasionally); calcareous. Typically sparse or uncommon; found with other sedges such as C. membranacea and C. aquatilis var. minor along stream margins, lake shores; wet sand or gravel. Sometimes found in saturated peat or muck. It can occur in areas extensively grazed by muskoxen.
North American distribution. Alaska, Yukon, Northwest Territories Islands, continental Northwest Territories, Nunavut Islands, continental Nunavut, northern Quebec, Labrador (?). Range in the Canadian Arctic Archipelago widespread. Common. Arctic. Arctic islands: Baffin, Devon, Ellesmere, Banks, Victoria, Southampton, and Coats (Boothia and Melville peninsulas).
Northern hemisphere distribution. Circumpolar, or circumboreal. Northern Fennoscandian, Polar Ural Novaya Zemlya, Taimyr Severnaya Zemlya, AnabarOlenyok, Kharaulakh, West Chukotka, Wrangel Island, South Chukotka, East Chukotka, West Alaska, North Alaska Yukon, Central Canada, Labrador Hudson Bay, Ellesmere Land Peary Land, West Greenland, East Greenland.
General notes. Polunin (1940) noted that this species may be mistaken for a marsh form of Carex fuliginosa [as C. misandra] and that specimens of the two are sometimes mounted together; upon closer examination they are actually quite distinct.
In a study of scale-dependent correlations of Arctic vegetation and snow cover in southeastern Victoria Island, Schaefer and Messier (1995) found that C. atrofusca exhibited positive associations with various measures of snow cover. It is thought that snow cover may reduce the rate of desiccation, protect plants from abrasion, and insulate them from low temperatures.
Rare exceptions to the normal morphology are the specimens CAN 23127 and CAN 483451, with two staminate spikes, and CAN 483450, which has a subterminal spike with both staminate and pistillate flowers.
Ball and Mastrogiuseppe (2002) noted that C. atrofusca is the only species in sect. Aulocystis with papillose perigynia, suggesting that it is perhaps misplaced. Egorova (1999, in Elven et al. 2003) placed C. atrofusca in sect. Chartoteuchium.
Illustrations. • Habitat. Gravelly meadow. Nunavut, Baffin Island, Iqaluit. 24 July, 1982. J.M. Gillett 19023. CAN. • Close-up inflorescence. Inflorescence with terminal spike totally staminate and proximal pistillate spikes. Nunavut, Baffin Island. 14 July, 2004. Aiken and LeBlanc 04–088. CAN 586559. • Close-up of inflorescence. Staminate terminal spike at anthesis. Lower spike pistillate. Perigynia with long beaks. Stigmas 2. Nunavut, Baffin Island, Ogac Lake. Aiken and LeBlanc 04–088. CAN 586559. • 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..