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 aquatilis Wahlenb. subsp. stans (Drejer) Hultén

English: Aquatic sedge,

French: Carex aquatique,

Inuktitut: Kilirnait, iviit, ivisuka, ivitsuskaka.

Cyperaceae, Sedge family.

Published in Circumpolar Pl. 1: 74. 1962.

Type: Described from Greenland.

Synonymy. Carex stans Drejer, Naturhist. Tidsskr. 3: 40. 1841.

Carex concolor R. Br., in Parry, Voy. App. 283. 1823.

Carex rigida Gooden. var. concolor (R. Br.) Kükenthal, in Engl., Pflanzenreich 38.IV, 20: 301.1909.

Carex aquatilis Wahlenb. var. minor Boott, 3. Gen. Carex pt. 4: 163. 1867.

Vegetative morphology. Plants (5–)15–30(–40) cm high (in the Arctic islands, to 150 cm tall on continental North America); perennial herbs; not caespitose. Only fibrous roots present. Roots pallid-brown. Ground level or underground stems horizontal; rhizomatous, or stoloniferous; elongate. Ground level or underground stems scales present (light brown and striate). Aerial stems erect, or decumbent (new growth); not filiform. Leaves present; mainly basal; alternate; marcescent. Petioles absent. Sheaths present; persisting (breaking down into fibres after more than a year); forming a conspicuous build-up at the base of the plant; brown, or reddish orange (sometimes pale purplish); glabrous (with a concave apex); sheath collars absent. Ligules present. Leaves grass-like. Blades 30–100(–250) mm long, (0.5–)1.5–4.5 mm wide, straight, linear, flat or revolute or folded (loosely), veins parallel, septate nodulose (seen on the adaxial surface at 10× as "indistinct spots"). Blade adaxial surface glabrous. Blade abaxial surface glabrous (amphistomatic and papillose on both surfaces). Blade margins scabrous (scaberulous at the tip); apices acuminate.

Reproductive morphology. Plants monoecious. Flowering stems triangular in cross section (hollow in the centre). 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; exceeding the inflorescence; 30–120(–130) mm long; persistent; sheathless (the base of the blade may enclose the stem at the node, but there is no sheath covering any part of the internode). Inflorescences a spike of spikes; (2–)4–10(–12) cm long; 5–15 mm wide. Pedicels glabrous. Cladoprophylls present. Inflorescence multispicate. Inflorescence 2–5 spikes. Individual spike(s) erect, or ascending (lateral spikes pistillate 20–40 mm long × 4–7 mm wide). Terminal spike completely staminate. Floral scales as long as the perigynium in fruit (the green sides of perigynia are visible around the edges of the darker scales); brown (red to purplish brown); with margins the same colour as the body of the scale; ovate (broadly, or oblong); 1.5–2 mm long; 0.7–0.9 mm wide; glabrous; apex obtuse. Flowers unisexual. Staminate flowers conspicuous. Perianth represented by a perigynium. Stamens present (staminate flowers), or absent (pistillate flowers); 3. Anthers 2.8–3.2 mm long. Ovary superior; carpels 3; syncarpous. Perigynia sessile. Styles 2; partially fused; slender, not extending beyond the beak. 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; broadly ovate; 2.2–2.8(–3.2) mm long; 1.2–1.6 mm wide; erect or ascending; golden brown, or green (blotched); membranous; surface glossy; glabrous; papillose; appearing veinless; with 2 keels; apices beaked with a short beak. Fruit sessile; dry; an achene; indehiscent. Achenes lenticular (somewhat flattened; not constricted); filling the perigynia (loosely). Seeds 1.

Chromosome information. 2n = 76 and 80.

2n = 76. Holmen (1952, Greenland); Jørgensen et al. (1958, Greenland); Löve and Solbrig (1965a), Löve (1981d, northern Canada); Löve and Ritchie (1966, central Canada); Krogulevich (1971, Siberia; 1976, northern Siberia); Zhukova and Petrovsky (1971, Wrangel Island; 1977, northeastern Asia); Packer and McPherson (1974, northern Alaska); Zhukova et al. (1977, northeastern Asia); Yurtsev and Zhukova (1978, Chukotka); Zhukova (1980, southern Chukotka); Petrovsky and Zhukova (1981, Wrangel Island); Dalgaard (1989, western Greenland).

2n = about 80. Johnson and Packer (1968, northwestern Alaska).

2n = 26 Löve and Solbrig, 1965 (Canada: Manitoba, Churchill, J.C. Ritchie 976. MAN);

2n = 76 Löve, 1965 (Canada, : Manitoba, Churchill, J.C. Ritchie 976. MAN).

Ecology and habitat. Substrates: wet meadows (sometimes below snow banks), hummocks (frost boils), around the margins of ponds, depressions of low-centre polygons, marshes (often extensive), along streams (on poorly drained sandy berms; also on the sides of steep gullies), river terraces, lakeshores (plants emergent, or in moist areas), tundra, seashores (in coastal flats, beach ridges and swales, and by the mouths of streams); aquatic, imperfectly drained moist areas, seepage slopes; rocks (carbonate plates, cobble, or bare bedrock), gravel, sand, silt, clay, till (or various combinations of the above); peat (with Sphagnum), with low organic content (for example, on bare wet sand), with high organic content; calcareous, or halophytic (and just as often indifferent and in mesotrophic peat (Elven, personal communication, 2005)). Often locally dominant in mixed Carex and Eriophorum meadows, often grazed by muskoxen; also found with low Salix shrubs, Arctophila fulva, Dupontia fisheri, and occasionally Sphagnum. When it grows near the coast, it is usually found in freshwater wetlands (Gadallah and Jefferies 1995). Although most often a plant of moist places, C. aquatilis var. minor can occasionally be found in dry slopes and plains. From a broader geologic perspective, this species is found on silty till plains, and alluvial outwash. It has been reported on the sides of drumlins and on colluvium slopes at the bases of cliffs.

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, Axel Heiberg, Parry islands, Cornwallis, Banks, Victoria, Prince of Wales, Somerset, King William, Southampton, and Coats (as well as Prince Charles and Stefansson).

Northern hemisphere distribution. Circumpolar. Northern Fennoscandian (?), Kanin–Pechora, Svalbard – Franz Joseph Land, Polar Ural – Novaya Zemlya, Yamal–Gydan, Taimyr – Severnaya Zemlya, Anabar–Olenyok, Kharaulakh, Yana–Kolyma, 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. The Flora of North America treatment (Standley et al. 2002) states that the species C. aquatilis is distinguished by "amphistomic... papillose leaves, glabrous sheaths with a concave apex, and perigynia that lack veins and are usually brown-spotted in the proximal half, and have glossy achenes," and recognises four extensively intergrading varieties. The one that occurs in the Arctic Archipelago, although extensively intergrading along the Arctic coast with var. aquatilis, appears to be distinct, as it has been reported to maintain its distinctive characteristics in cultivation (Cayouette and Morisset 1986).

The entity that occurs in the Canadian Arctic is called C. aquatilis var. minor Boott in the Flora of North America treatment (Standley et al. 2002). Elven et al. (2003) recognise this taxon as subsp. stans (Drejer) Hultén, with the comment that "the division into aquatilis and stans seems to be made differently in different areas. In Norway and Greenland, and partly in North America, 'minor' is considered fairly narrowly whereas some Russian floras [Fl. Murm. Obl.] consider it much more widely 'stans'. This results in discrepancies at national borders". If subsp. stans is raised to species, the name C. concolor R. Br. has priority (Egorova, personal communication, 2002).

The role of this taxon (as C. aquatilis var. minor) in methane efflux from boreal peat lands was studied by Pullman et al. (1995).

In a study of scale-dependent correlations of Arctic vegetation and snow cover in southeastern Victoria Island, Schaefer and Messier (1995) found that this taxon (as C. aquatilis var. minor) 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 from low temperatures.

Carex aquatilis s.l. is a forage species for lesser snow geese (Anser caerulescens). In their study of the nutrient contents of principal forage plants utilised by the geese at La Perouse Bay, Manitoba, Gadallah and Jefferies (1995) show that nutrient content in C. aquatilis s.l. is lower than that of C. subspathacea, which inhabits salt marshes nearer to the coast. Although the lesser snow goose prefers to forage on C. subspathacea, it will feed on the leaf tips of C. aquatilis during the summer and on the shoot bases and rhizomes in spring and autumn.

Carex aquatilis was found to be an early coloniser of oil spills in Alaska (Kershaw and Kershaw 1986).

Ovenden (1986) found Carex aquatilis s.l. was an early colonising species on the lake bed of Illisarvik, the site of a thermokarst lake that was artificially drained in August 1978. By 1985, the lake bed was dry in most areas and wind erosion was extensive. Substrate type appeared to have had little influence on distributional patterns of the colonising vegetation. More important factors were probably erosion, surface wetness, and proximity of the lake-bed margin. Other widespread species included Tephroseris palustris subsp. congesta (Senecio congestus), Descurainia sophioides, Tripleurospermum maritimum, Artemisia tilesii, Arctophila fulva, and Stellaria longipes.

Illustrations. • Habitat: Baffin Island, Cape Dorset. Yellow-green plants near the marker forming a dominant zone in low lying places of a sedge meadow beside a lake. Nunavut, Baffin Island, Cape Dorset. 3 August, 2005. Aiken. No voucher. • Habitat: Patterned ground. Yellow-green plants growing in patterned ground beside lake. Nunavut, Baffin Island, Cape Dorset. 3 August, 2005. No voucher. • Habitat: Ellesmere. Conspicuously small plants, less than 15 cm high in the High Arctic. Growing in a small area on calcareous gravel and silt in a seasonally wet meadow. Nunavut, Ellesmere Island, Scoresby Bay. Aiken 98–010. CAN. Photograph by Mollie MacCormac. Scale bar in cm. • Close-up of plant. Plants about 10 cm high with flowering spikes at anthesis. Nunavut, Ellesmere Island, Scoresby Bay. Aiken 98–010. CAN. Photograph by Mollie MacCormac. Scale bar in cm. • Close-up of plants. Plants at anthesis growing on silt near a pond. Leaf associated with the inflorescence extending beyond it. Terminal spike male, lower spikes female. N.W.T., Banks Island, Sachs Harbour. 24 July, 1981. J.M. Gillett 18792. CAN. • Close-up of inflorescence. Compact inflorescence with little distance between the 4 to 5 spikes. Terminal staminate spike with prominent yellow anthers, lower spikes showing perigynia with two stigmas. Nunavut, Ellesmere Island, Scoresby Bay. Aiken 98–010. CAN. Photograph by Mollie MacCormac. • Type specimen of hybrid. Holotype of hybrid Carex xstansalina E. Lepage, C. aquatilis x C. subspathacea. Nat. Can. 83:150.1956. Southampton Island, H.B.Co. Post, South Bay. 25 August, 1934. Nicholas Polunin s.n. CAN 25083. • 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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