Carex atrofusca Schkuhr
Cyperaceae, sedge family.
Riedgr. 1: 106. 1801.
Nomenclatural section used by Flora of North America project subgenus Carex, sect. Aulocystis Dumortier
Carex ustulata Wahlenb.
Type: Described from Austria: Kärnten, type in HAL.
Vegetative morphology. Plants perennial herbs; (6–)15–30 cm high; caespitose (loosely); with erect, slender, smooth culms. Roots pallid-brown. Ground-level or under-ground stems horizontal, or not developed horizontally or vertically; compact. Scales present. Aerial stems decumbent; not filiform; triangular in cross-section; glabrous. Leaves in a basal tuft; simple. Petioles absent. Sheaths persisting (breaking into fibres after the first year); not forming a conspicuous build up at the base of the plant; brown; collars absent. Ligules present. Blades 20–130 mm long; 1.5–3.5 mm wide. Blades straight; linear; flat, or revolute (glaucous); veins parallel. Blades adaxial surface glabrous. Blades abaxial surface glabrous. Blade margins scabrous (scaberulous at the tip).
Reproductive morphology. Plants monoecious. Flowering stems present. Flowering stems conspicuously taller than the leaves; with leaves; glabrous. Leaf or reduced bract closely associated with 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; with sheath shorter than the blade; persistent. Inflorescence spicate; 2–3.5 cm long; 20–30 mm wide. Pedicels glabrous (capillary). Inflorescence multispicate; 2–4 spikes; lateral spikes borne on pedicels. Individual spike(s) erect (dwarf specimens), or pendent. Terminal spike wholly staminate, or staminate at the apex (club-shaped, rarely two spikes have staminate flowers). Cladoprophyll present at the base of the peduncle of lateral spikes. Staminate flowers conspicuous (usually). 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. Perianth absent. Flowers unisexual. Stamens 3. Anthers 1.5–3.5 mm long. Carpels syncarpous. Styles slender, not extending beyond the beak. Stigmas per style 3. Placentation basal. 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; sessile; erect or ascending; black; membranous; surface dull; glabrous; appearing nerveless; not keeled (scaberulous towards the apex); apices beaked with a long beak; apex deeply bidentate. Fruit an achene. Achenes not filling the upper part of the perigynia; trigonous.
Chromosome information. 2n = 36 (-38-42). Heilborn (1924, 1928 northernorthern Europe, 2n = 36); Sørensen and Westergaard in Löve and Löve (1948 Greenland, 2n = 40); Jørgensen et al. (1958 Greenland); Dietrich (1964, 1967, 2n = 40); Löve and Löve (1965, 1966b); Löve and Ritchie (1966 northern Canada); Knaben and Engelskjøn (1967 southern and northern Norway); Hedberg (1967 northern Canada, 2n = c.42); Johnson and Packer (1968 northwestern Alaska ); Zhukova (1969 north eastern Asia, 1980 S Chuk); Krogulevich (1976 northern Siberia); Löve and Löve (1981c northern Canada); Malychev (1990).
Distribution. Northern hemisphere distribution: circumpolar; Greenland, Canada. Yukon, Northwest Territories Islands, Continental Northwest Territories, Nunavut Islands, Continental Nunavut, Northern Québec (Boothis Peninsula). Arctic. Range in the Canadian Arctic Archipelago widespread. Common. Arctic Islands: Baffin, Devon, Ellesmere, Banks, Victoria, Southampton, and Coats.
Ecology and habitat. Substrates: wet meadows, hummocks, marshes, along streams, river terraces, lake shores, tundra; imperfectly drained moist areas, or on seepage slopes; calcareous; gravel, sand, silt, till (often on till plains), moss; with high organic content, or peat (occasionally). Habitats: Typically sparse or uncommon; found with other sedges such as C. membranacea and C. aquatilis var. stans along stream margins, lake shores; wet sand or gravel. Sometimes found in saturated peat or muck. It can occur in areas extensively grazed by musk oxen.
Notes. Polunin (1940) noted that this species may be mistaken for a
marsh form of Carex fuliginosa and that specimens of the two are
sometimes mounted together, although in the field they have practically no
resemblance to one another.
In a study of scale-dependent correlations of
Arctic vegetation and snow cover in south-eastern 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.
Specimens with two staminate spikes CAN 23127, CAN 483451.
Specimen with a subterminal spike, with both staminate and pistillate flowers,
CAN 483450.
Variety major is considered to be no more than larger
plants from more favorable environments (P. Ball personal communication April
1998).
Illustrations. • Plants in habitat. Gravelly meadow. Nunavut, Baffin Island, Iqaluit, July 24, 1982, J.M. Gillett 19023, CAN. • Close-up plants. Plants showing several drooping spikes on each inflorescence. Apex, Baffin Island, Nunavut, 28 Aug. 1997, Aiken 97–063, CAN. Scale bar in cm. • Close-up of inflorescence. Inflorescence typically with one male (apical) spike and two female (lateral) spikes. Norway: Troms, Tromsoe, Floya. 31.07.1978. Photographed by R.Elven. • Close-up inflorescence. Inflorescences with lighter brown, terminal male spikes and dark brown female spikes. Plant collected beside seepage runoff near Apex, Baffin Island, Nunavut, 28 Aug. 1997, Aiken 97–063, CAN. • Close-up of Inflorescence. Herbarium specimen showing inflorescence with uppermost spike at anthesis not drooping in this drawf plant. Lower spikes pistillate: perigynia with long beaks. • Close-up of Inflorescence. Mature spike with perigynia sessile or almost sessile on the rachis. • 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).
