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

Eleocharis acicularis (L.) Roemer and J.A. Schultes

English: Needle spike rush,

French: Éléocharide aciculaire,

Inuktitut: Iviit, ivisuka, ivitsuskaka.

Cyperaceae, Sedge family.

Published in Syst. Veg., ed 15, 2: 154. 1817.

Type: Described from Europe.

Synonymy. Scirpus acicularis L., Sp. Pl. 48. 1753.

Eleocharis acicularis f. submersa (Hj. Nilss.) Norman, in Christ. Vidensk.-Selsk. Förh. 16: 43. 1893–94.

Vegetative morphology. Plants 2.5–10 cm high (-60 cm tall in continental North America); perennial herbs; not caespitose. Only fibrous roots present. Roots pallid-brown. Ground level or underground stems horizontal; rhizomatous, or stoloniferous (depending on the substrate); compact; 0.25–0.5 mm wide. Ground level or underground stems scales present (on horizontal stems, translucent, rarely evident 2 mm). Aerial stems erect; filiform ((0.1–0.25 (-0.5) mm in diameter; internodes 5–15 mm). Leaves mainly basal; alternate; dying annually and non-persistent. Petioles absent. Sheaths present; breaking down into fibres; not forming a conspicuous build-up at the base of the plant; brown, or reddish orange (Reddish towards the outside, colourless or whitish, towards the centre of the plant, apex rounded to acute); with the margins fused to the apex, or with the margins fused only in the lower part (often splitting adaxially); glabrous; sheath collars absent. Ligules present. Leaves grass-like. Blades 5–10(–60) mm long, 0.4–0.6 mm wide. Leaves filiform. Blades straight, linear, circular in cross section (pressing flat), veins parallel. Blade adaxial surface glabrous. Blade abaxial surface glabrous. Blade margins glabrous.

Reproductive morphology. Flowering stems circular or oval in cross section (sometimes distinctly compressed), (0.2-)0.5(-0.7 mm) wide.). Flowering stems about as high as the leaves; without leaves. Leaf or reduced bract subtending the base of the inflorescence absent (spike terminal). Inflorescences spicate (with a single spike); dense; 0.3–0.6 cm long; 1–2 mm wide. Inflorescence unispicate. Terminal spike with both sexes in each floret (no fertile specimens are known from the Arctic Archipelago). Involucral bracts absent. Floral scales green (reddish); with margins and sometimes midvein paler in colour than the adjacent area of the scale; ovate, or lanceolate; 2–3 mm long; 1.2–1.8 mm wide; glabrous. Perianth represented by bristles (the "cotton" of cotton grasses). Perianth bristles inconspicuous. Sepals modified (but not a pappus). Stamens 3. Anthers 1–1.4 mm long. Ovary carpels 3; syncarpous. Styles 3; free, or partially fused (base an enlarged bulge, separated from the top of the achene). Stigmas per ovary 3. Placentation basal. Ovules per ovary 1. Fruit sessile; surrounded by a perianth persisting as bristles; dry; an achene; straw-coloured; 0.9–1.1 mm long; indehiscent. Seeds 1.

Chromosome information. 2n = 18-20, about 56.

2n = 18-20.

2n = 20. Tanaka (1937, 1948); Löve and Löve (1956, Iceland); Löve (1981d, central Canada; 1982c, eastern Canada); Jørgensen et al. (1958, Greenland); Strandhede (1965, northern Europe); Taylor and Mulligan (1968, western Canada); Zhukova and Petrovsky (1976, western Chukotka); Kozhevnikov et al. (1986, northeastern Asia, 2n = about 18–20); Dalgaard (1989, western Greenland). Several more southern counts of 2n = 20.

2n = about 56. Hicks (1929, 2n = 36–38, 50–58, 56); Tischler (1934); Rohweder (1937, central Europe).

Ecology and habitat. Substrates: wet meadows, around the margins of ponds; aquatic; silt; with high organic content; halophytic. Forms soft green carpets on the bottom of ponds near Carex chordorrhiza. In the Great Plain of the Koukdjuak, it was found localised in an expansive saline plain, growing thinly in bare clay with occasional Chrysosplenium tetrandrum (Boles observation).

North American distribution. Alaska, Yukon, continental Northwest Territories, Nunavut Islands, continental Nunavut, northern Quebec, Labrador. Range in the Canadian Arctic Archipelago limited. Rare. Low Arctic. Arctic islands: Baffin (Iqaluit, Great Plain of the Koukdjuak (both new since Porsild 1957) and Kimmirut).

Northern hemisphere distribution. Circumboreal. Northern Iceland, Northern Fennoscandian, Kanin–Pechora, Yamal–Gydan, Anabar–Olenyok, Yana–Kolyma, West Chukotka, Wrangel Island, South Chukotka, East Chukotka, West Alaska, North Alaska – Yukon, Central Canada, Labrador – Hudson Bay, West Greenland, East Greenland.

General notes. Polunin (1940) noted that this plant was first found in the Canadian Arctic Archipelago at Kimmirut in 1936, submersed in small freshwater ponds in marshy lowland areas a few miles inland. It has since been found in Iqaluit. In the Arctic Archipelago, as is usually the case in Greenland, the plants are submersed and entirely sterile.

Eleocharis acicularis is abundant and ecologically important throughout much of its southern range. Submerged, usually non-flowering plants have been distinguished as formas, e.g., forma inundata Svenson, forma submersa (Nilsson) Norman. "The culms of the submerged plants are terete, smooth, soft to flaccid, translucent and the partitions of the air cavities within are clearly visible... Much of the variation is apparently due to phenotypic plasticity in response to environmental factors, especially water depth...The named varieties intergrade extensively, and achenes, which are important in defining varieties, are often absent...Most plants from the Arctic to cool-temperate North America...have culms cylindrical or three- to four-angled; leaf sheaths mostly obscure and closely sheathing; and achenes about two times longer than wide." (Smith 2002, pp. 109). Polunin (1940) suggested that these submerged plants might be recognised as E. acicularis f. submersa (H. Nilss.) Norman, but taxonomic recognition is not appropriate, as the plants are merely the underwater form.They are similar to the type that was described from Europe.

Illustrations. • Close-up of plant. Plant from muddy river bank. Norway, Finnmark, Kautokeino Saami church village. 26 July, 1980. Photograph by R. Elven. Voucher at TROM. • Habitat. Stand of flowering plants growing on an expanding shore of a naturally draining lake. Alaska, Tanana Valley, Harding Lake. July, 2001. Photograph by Heidi Solstad. Voucher at 0. • Plants at anthesis. Flowering plants on an expanding shore of a naturally draining lake. Note exserted anthers and stigmas. Alaska, Tanana Valley, Harding Lake. July, 2001. Photograph by Heidi Solstad. Voucher at 0. • Close-up of flowers. Plants 3–4 cm tall with spikes 1–1.5 mm. Left, three exerted anthers. Alaska, Tanana Valley, Harding Lake. July, 2001. Photograph by Heidi Solstad. Voucher at 0. • 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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