Flora of the Canadian Arctic Archipelago

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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 holostoma Drejer

English: Arctic marsh sedge, holostome sedge,

French: Carex à bec entier,

Inuktitut: Iviit, ivisuka, ivitsuskaka.

Cyperaceae, Sedge family.

Published in Naturhist. Tidsskr. 3: 29. 1841.

Type: Described from Greenland. Holotype: C.

Vegetative morphology. Plants (10–)15–20(–30) cm high; perennial herbs; not caespitose (loosely tufted and long rhizomatous). Only fibrous roots present. Roots pallid-brown. Ground level or underground stems horizontal; rhizomatous, or stoloniferous; elongate. Ground level or underground stems scales present (on stolons). Aerial stems erect; not filiform (0.8–1.5 mm in diameter,). Leaves present; mainly basal; alternate; marcescent. Petioles absent. Sheaths present; persisting; not forming a conspicuous build-up at the base of the plant; brown, or reddish orange (sometimes purplish basal sheaths); sheath collars absent. Ligules present; membranous. Leaves grass-like. Blades 40–120 mm long, 0.5–3(–4) mm wide, straight, linear, flat or revolute (slightly), veins parallel. Blade adaxial surface glabrous. Blade abaxial surface glabrous (but minutely scaberulous on midvein and margins). Blade margins scabrous (scaberulous); apices acuminate.

Reproductive morphology. Plants monoecious. Flowering stems two or more per plant. Flowering stems triangular in cross section. Flowering stems conspicuously taller than the leaves (usually); with leaves. Leaf or reduced bract subtending the base of the inflorescence present; conspicuous and leaf-like, or reduced, or scale-like; exceeding the inflorescence (rarely), or similar in length to the inflorescence, or shorter than the apex of the inflorescence (usually); 5–35 mm long; persistent (but withering to become inconspicuous); with sheath shorter than the blade. Inflorescences a spike of spikes (very compact; all spikes of equal length); 1–2.5 cm long; 8–12 mm wide. Pedicels glabrous (short, so that the inflorescence is head-like). Cladoprophylls present. Inflorescence multispicate. Inflorescence 2–3 spikes (of similar lengths 3–8 mm long × 2–2.5 mm wide). Individual spike(s) ascending. Terminal spike completely staminate (spike may be hidden by larger, overtopping 1–2(-3) lateral pistillate spikes). Floral scales shorter than the perigynium in fruit, or as long as the perigynium in fruit; brown, or black; with margins and sometimes midvein paler in colour than the adjacent area of the scale (the transparent marginal zone very narrow; the midvein conspicuous, sometimes raised and mucronate); ovate; 1.5–2 mm long; 1–1.5 mm wide; glabrous. Flowers unisexual. Staminate flowers inconspicuous (small, the spike often concealed between the pistillate spikes). Perianth represented by a perigynium. Stamens present (staminate flowers), or absent (pistillate flowers); 3. Anthers 1.5–2 mm long. Ovary superior; carpels 3; syncarpous. Perigynia sessile. Styles 2; partially fused; thick and short. Stigmas per ovary 2. 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; obovate; 1.8–2(–2.5) mm long; 1–1.2(–1.7) mm wide; erect or ascending; brown, or green; membranous; surface dull; papillose; faintly veined, or appearing veinless (if immature); not keeled; apices merely conical or rounded (or abruptly beaked with truncate beak to 0.2 mm long). Fruit sessile; dry; an achene; indehiscent. Achenes trigonous; filling the perigynia. Seeds 1.

Chromosome information. 2n = 54–60.

2n = 54–60.

2n = 54. Löve and Löve (1956, Iceland); Krogulevich (1976, northern Siberia, 2n = about 54); Yurtsev and Zhukova (1982, northern Siberia, 2n = 54);

2n = 56. Zhukova and Tikhonova (1971, Chukotka); Zhukova (1980, southern Chukotka); Dalgaard (1989, western Greenland); Engelskjøn and Knaben (1971, northern Norway, 2n = 58–60);

2n = 60. Jørgensen et al. (1958, Greenland); Löve (1970a, Iceland); Zhukova and Petrovsky (1975, western Chukotka, 2n = 60); Löve (1981d, central Canada).

Ecology and habitat. Substrates: hummocks (turfy places in the tundra and by the edge of small ponds), around the margins of ponds, river terraces; imperfectly drained moist areas, seepage slopes; acidic (a ‘pronounced acidophyte’, Porsild 1957). It has also been reported from a calcareous fen (CAN 259414).

North American distribution. Alaska, Yukon, Northwest Territories Islands (?), continental Northwest Territories, Nunavut Islands, continental Nunavut, northern Quebec, Labrador (?). Range in the Canadian Arctic Archipelago limited. Uncommon. Low Arctic. Arctic islands: Baffin (Beekman Peninsula, Kimmirut and Ogac Lake), Southampton, Victoria (Surrey Lake; a new collection (CAN 526808) since Porsild (1957), which extends the range considerably. The specimen was annotated as this name by T. Spribille, 1997).

Northern hemisphere distribution. Circumpolar (with large gaps). Yamal–Gydan, Taimyr – Severnaya Zemlya, West Chukotka, South Chukotka, East Chukotka, West Alaska, North Alaska – Yukon, Central Canada, Labrador – Hudson Bay, West Greenland.

General notes. Polunin (1940) noted that this taxon was frequently classified as a variety of C. norvegica, but in the field it is entirely distinct and he had seen no transitional forms.

Murray (2002) noted that C. holostoma has most likely been overlooked and has a more continuous range than indicated.

Illustrations. • Habitat: Ogac Lake. Plants growing beside and near the marker in black muck at the bottom of a drained spring standing water puddle. Nunavut, Baffin Island, Ogac Lake. 11 July, 2004. Aiken and LeBlanc 04–068. CAN 586537. • Close-up of plant. Plant growing beside the marker in black muck at the bottom of a drained spring standing water puddle. Nunavut, Baffin Island, Ogac Lake. 11 July, 2004. Aiken and LeBLanc 04–068. CAN 586537. • Rhizomes at base of plant. Sedge with horizontal ground level stems and compact multispicate inflorescences. Nunavut, Southampton Island, Coral Harbour. A.E. Porsild 21706. CAN 259414. • Close-up of inflorescence. Note leaf-like bract subtending the 3 ascending spikes. Terminal spike completely staminate. Pistillate flowers with black scales and obovate perigynia with apices abruptly beaked. Achenes trigonous, filling the perigynia. Aiken and LeBlanc 04–068. CAN 586537. • Close-up of compact inflorescence. Note reduced leafy bract high on the flowering culm. Inflorescence a very compact head-like spike of 2–3 ascending spikes, all of equal length. Terminal spike completely staminate, inconspicuous, concealed between the pistillate spikes. Pistillate flowers with black scales and obovate perigynia. Achenes trigonous, filling the perigynia. Aiken and LeBlanc 04–068. CAN 586537. • 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.

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