Flora of the Canadian Arctic Archipelago


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

Carex L.

English: Sedge,

Inuktitut: Iviit, ivisuka, ivitsuskaka.

Cyperaceae, Sedge family.

Published in Sp. Pl. 972. 1753.

Vegetative morphology. Plants 2–30(–90) cm high (mean about 20 cm); perennial herbs; caespitose, or not caespitose. Only fibrous roots present. Roots yellow (tomentose), or pallid-brown (most often), or red-brown, or black. Ground level or underground stems horizontal, or absent; rhizomatous, or stoloniferous; elongate, or compact (yellow-brown); not more than 1.4 mm wide. Ground level or underground stems scales present, or absent (usually). Aerial stems erect, or ascending, or decumbent; filiform, or not filiform. Leaves mainly basal, or distributed along the stems; alternate; dying annually and non-persistent and marcescent. Petioles absent. Sheaths present; persisting, or breaking down into fibres; forming a conspicuous build-up at the base of the plant, or not forming a conspicuous build-up at the base of the plant; greyish brown, or brown, or green, or reddish orange (purple, e.g., C. scirpoidea); glabrous, or with trichomes (rarely); sheath collars absent (usually). Ligules present; 0.1–1 mm long (the ligule flap; to 10 mm long when the shape of the insertion is measured); membranous; glabrous; ovate-oblong, or transversely oblong. Ligule apices acute, or obtuse, or truncate. Leaves grass-like. Blades (5–)10–250(–440) mm long, 0.2–6.3 mm wide (mean 1.6 mm), appressed to the stem or spreading, straight or somewhat curled, folded in bud (V-shaped in cross section when young), linear, flat or bristle-like or strongly keeled or involute or revolute or folded or channelled, veins parallel, septate nodulose (rarely) or not septate nodulose. Blade adaxial surface dull (usually) or glaucous, glabrous or scabrous. Blade abaxial surface glaucous or not glaucous, glabrous or scabrous. Blade margins entire or serrate (at the apex, if applicable), scabrous (scaberulous at the tip) or glabrous; apices acuminate.

Reproductive morphology. Plants monoecious, or dioecious. Flowering stems triangular in cross section, or circular or oval in cross section. Flowering stems shorter than the leaves, or about as high as the leaves, or conspicuously taller than the leaves; with leaves (usually associated with lateral spikes when these are present), or without leaves (rarely), or without leaves in the upper half (if the inflorescence is a solitary spike). Leaf or reduced bract subtending the base of the inflorescence present, or absent; conspicuous and leaf-like, or reduced, or scale-like; exceeding the inflorescence, or similar in length to the inflorescence, or shorter than the apex of the inflorescence; (2–)10–190 mm long; persistent; with sheath longer than the blade, or with sheath shorter than the blade, or sheathless. Inflorescences spicate, or head-like, or a spike of spikes, or a raceme of spikes; 0.4–15(–20) cm long (mean 3.5 cm approximately); 1.5–15(–50) mm wide (mean approximately 11 mm). Pedicels glabrous, or scabrous. Cladoprophylls present (Subgenus Carex), or absent (Subgenus Vignea). Inflorescence unispicate, or multispicate. Inflorescence 1–8 spikes. Individual spike(s) erect, or ascending, or divergent, or pendent. Terminal spike staminate at the base, or completely staminate, or staminate at the apex, or pistillate (rarely). Floral scales shorter than the perigynium in fruit, or as long as the perigynium in fruit, or longer than the perigynium in fruit (rarely); brown, or black, or orange-brown, or green, or white or translucent; with margins the same colour as the body of the scale, or with margins and sometimes midvein paler in colour than the adjacent area of the scale, or with margins darker in colour than the midvein, or with margins paler than body of the scale; reflexed (rarely), or not reflexed; ovate, or lanceolate, or obovate; falling early, or not falling early (usually); 1–5.5 mm long; 0.7–3.4 mm wide; glabrous, or hairy all over (rarely); apex rounded, or retuse, or obtuse, or cuspidate, or acute. Floral bracts hairs very dense (C. scirpoidea). Flowers unisexual. Staminate flowers inconspicuous, or conspicuous. Perianth represented by a perigynium. Stamens present (staminate flowers), or absent (pistillate flowers); 3. Anthers 0.8–4.1 mm long. Ovary superior; carpels 3; syncarpous. Perigynia contracted at the base into a stipe, or sessile. Stipes 0.1–0.7 mm long (if applicable). Styles 2, or 3; partially fused; thick and short, or slender, not extending beyond the beak, or slender, extending beyond the beak, or long and thick (rarely). Stigmas per ovary 2, or 3. Placentation basal. Ovules per ovary 1. Fruit surrounded by a perigynium (an inflated sac surrounding the ovary). Perigynia with a slit running down the beak on the abaxial side through which the style protrudes, or fused to the apex except for a small aperture through which the style protrudes; globose, or sub-globose, or lanceolate, or broadly ovate, or obovate, or elliptic; 1.5–6 mm long (mean 3 mm); 0.5–3 mm wide; erect or ascending, or reflexed (rarely), or spreading at maturity; black, or straw-coloured, or golden brown, or brown, or green, or whitish; membranous (usually), or leathery; surface glossy, or surface dull; glabrous, or hairy (rarely), or scabrous; tuberculate, or papillose, or serrulate; strongly veined, or faintly veined, or appearing veinless; inflated (rarely), or not inflated; not keeled, or with 2 keels, or with 3 keels (rarely); apices beaked with a long beak, or beaked with a short beak, or merely conical or rounded; apex oblique, becoming slightly bidentate, or deeply bidentate, or not bidentate or oblique. Fruit sessile; dry; an achene; ellipsoid, or ovoid, or obovate; indehiscent. Achenes lenticular, or trigonous; filling the perigynia, or not filling the upper part of the perigynia. Seeds 1; 1.1–2.2 mm long.

Chromosome information. 2n = 18–80.

General notes. The genus Carex includes the sedges that dominate wetlands, pastures, prairies, tundra, and the herb layer of temperate forests. There may be as many as 2000 species world-wide. Carex is one of the largest genera in the eastern Canadian flora, with approximately 300 species, and the largest genus in the Canadian Arctic Archipelago flora, with about 30 species.

Kükenthal (1909), in the only world-wide monograph of the genus, divided Carex into four subgenera: (1) Primocarex Kükenthal; (2) Vignea (P. Beauv. ex Lestib. f.) Peterm., (3) Indocarex Ballon, and (4) Carex. Kükenthal (1909) considered subg. Primocarex as primitive because its solitary terminal spike typically has a conspicuous secondary axis (rachilla), but subsequent authors (e.g., Reznicek 1990) believe the species in subg. Primocarex have evolved independently from multispicate species in other subgenera. Contrasting opinions about subgeneric classification have been expressed; many recent authors recognise three subgenera (Carex, Indocarex, and Vignea), with members of Primocarex placed variously in subg. Vignea or Carex or other closely related genera. This information on subgeneric classification within Carex was summarised from a more detailed discussion in Starr et al. (1999).

Starr et al. (1999) found that analyses of sequences of the internal transcribed spacer region (ITS) of nuclear ribosomal DNA was informative for inferring phylogenetic relationships among sections. They found two clades based on ITS sequence data: one with subg. Indocarex, Primocarex and a part of subg. Carex, and a second with sections from subg. Carex and subg. Primocarex. This evidence was consistent with theories that extreme inflorescence reduction has occurred several times in Carex, as subg. Primocarex and subg. Carex were polyphyletic.

Crins (1990) found that using character compatibility analysis of morphological characters had potential for determining phylogenetic relationships in the genus Carex below the sectional level. Starr et al. (1999) found that their ITS sequence data was not useful to fully resolve infrasectional relationships.

Bernard (1990), reporting on the life history and vegetative reproduction in Carex, observed that ‘they are modular organisms that reproduce vegetatively by rhizomes or other means’ (p. 1441). Some species form extensive and long-lived clones, others form tufts, clumps, or tussocks of various sizes. Most temperate and arctic species form shoots that either emerge in autumn or remain belowground until spring.

Anatomical aspects of the taxonomy of sedges were discussed by Standley (1990) who studied the anatomy of achene epidermis and leaves. She suggested that "single conical silica bodies and epapillose hypostomatous leaves are primitive character states in Carex. As both primitive and derived character states are widely distributed among sections, anatomical characters should not be generally applied as measures of similarity in phenetic approaches to classification, but they have potentially major importance in phylogenetic studies within and among sections" (p. 1449).

Many species have a relict rachilla, which is assumed to be the remains of the branch that bears staminate flowers in the perigynium of Kobresia (Peter Ball, personal communication, 1999).

Illustrations. • Habitat: Carex mackenziei.. Species is to be looked for in the western arctic islands. Circular colony of Carex mackenziei, dying out in the middle; brackish depression in a salt marsh. Norway, Nordland, Beiarn, Beiarosen. July, 1984. Photograph by H. Edvardsen. • Stand: Carex mackenziei. Profusely fertile stand in depression of a brackish marsh. The species is a specialist of brackish depressions with stagnant waters and anaerobic conditions. Norway, Troms, Lenvik. June, 1977. Photograph by R. Elven. • Close-up: Carex mackenziei. Vegetative and fertile shoots. Norway, Finnmark, Porsanger. July, 1983. Photograph by R. Elven.

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.