Eleocharis acicularis (L.) Roemer and J.A. Schultes
Cyperaceae, sedge family.
Syst. Veg. 2: 154. 1817
Scirpus acicularis L., Sp. Pl. 48. 1753
.
Vegetative morphology. Plants perennial herbs; 2.5–10 cm high (in the Arctic, to 60 cm tall further south); not caespitose; tiny aquatic perenials, with bristle-like leaves from a filiform rhizome buried in the mud. Roots pallid-brown. Ground-level or under-ground stems horizontal; rhizomatous, or stoloniferous (depending on the substrate); compact; 0.25–0.5 mm wide. Scales present (on horizontal stems, fugaceous, translucent, rarely evident 2mm). Aerial stems erect; not conspicuously jointed; filiform (0.1–0.2 mm in diameter); circular or oval in cross-section; with 3–12 ridges; sometime distinctly compressed, (0.2-)0.5(-0,7 mm wide. Leaves in a basal tuft; alternate; simple; existing for a single season or less. Petioles absent. Sheaths breaking down into fibres; not forming a conspicuous build up at the base of the plant; brown, or reddish (prominally stramineous to red, distally colourless or whitish, closely sheathed to prominently inflated, apex rounded to acute); with the margins fused to the apex, or with the margins fused only in the lower part (often splittting adaxially); glabrous; collars absent. Ligules present. Blades 10–60 mm long; 0.4–0.6 mm wide. Blades straight; linear; circular in cross section (pressing flat); veins parallel. Blades adaxial surface glabrous. Blades abaxial surface glabrous. Blade margins glabrous.
Reproductive morphology. Flowering stems present. Flowering stems about as high as the leaves; without leaves; glabrous. Leaf or reduced bract closely associated with the base of the inflorescence absent (spike terminal). Inflorescence spicate; dense; 0.3–0.6 cm long; 1–2 mm wide; a single spike. Terminal spike with both sexes in each floret (no fertile specimens are known from the Arctic Archipelago). Flowers small, less than 5 mm in diameter or length. 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; bristles inconspicuous. Stamens 3. Anthers 1–1.4 mm long. Carpels syncarpous. Stipes 3 mm long. Styles 3; base an enlarged bulge, separated from the top of the achene (which distinguishes this species from Trichophorum). Placentation basal. Fruit surrounded by a perianth persisting as bristles; an achene. Fruit 0.9–1.1 mm long; straw coloured.
Chromosome information. 2n = 18-20& c. 56.
18-20. - Tanaka (1937, 1948); Löve and Löve (1956b Iceland,
1981c central Canada, 1982c eastern Canada); Jørgensen et al. (1958
Greenland); Strandhede (1955b northernorthern Europe); Taylor and Mulligan (1968
western Canada); Zhukova and Petrovsky (1976 western Chukotka); Kozhevnikov et
al. (1986 north eastern Asia, 2n = c.18 20); Dalgaard (1989 western
Greenland). Several more southern counts of 2n = 20.
c.56. - Hicks
(1929, 2n = 36–38 50–58 56); Tischler (1934); Rohweder (1937
central Europe).
Distribution. Northern hemisphere distribution: circumpolar; Greenland, Canada. Continental Northwest Territories, Nunavut Islands, Continental Nunavut, Northern Québec. Low arctic. Range in the Canadian Arctic Archipelago limited. Rare. Arctic Islands: Baffin (Iqaluit, Great Plain of the Koukdjuak (both new since Porsild, 1957) and Kimmirut).
Ecology and habitat. Substrates: wet meadows, around the margins of ponds; aquatic; halophytic; silt; with high organic content. Habitats: Forms soft green carpets on the bottom of ponds near Carex chordorrhiza. In the Great Plain of the Koukdjuak, it was found localized in an expansive saline plain, growing thinly in bare clay with occasional Chrysosplenium tetrandrum.
Notes. Polunin (1940) noted that this plant was first found in the
eastern Canadian Arctic Archipelago at Kimmirut in 1936, submersed in bed of
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. He suggested that this
might be recognized as E. acicularis f. submersa (H. Nilss.)
Norman, but this has not been widely taken up, nor should it be as it is merely
the underwater form.
Porsild (1957), gave the authority for the generic name
as Linneaus, but this was a mistake as the genus was described by Robert Brown.
Eleocharis acicularis is abundant and ecologically important
throughout much of it's southern range. Submerged, usually non-flowering plant
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 partititions of the air cavities
within are clearly visible. Much of the vgariation is apparently due to
phenotypic plasticity in response to environment factos such as water depth. The
named varieties integrade extensively, and achenes that are important in
defining varieties, are often absent. Most plants from the Arctic to
cool-temperatue North America have clylindrical 3–4 anagled culms, leaf
sheaths mostly obscure and closely sheathing and achenes about two times longer
than wide. 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. 26/7–1980. Photo: R.Elven. Voucher in HbTROM. • Plant habitat. Flowering plants, stand. Alaska: Tanana Valley, Harding Lake, expanding shore of a naturally draining lake. July 2001. Photographed by Heidi Solstad. Voucher in HbO. • Plants at anthesis. Flowering plants, anthers and stigmas exerted. Alaska: Tanana Valley, Harding Lake, expanding shore of a naturally draining lake. July 2001. Photographed by Heidi Solstad. Voucher in HbO. • Close-up of flowers. Exerted anthers (3) and stigmas. Size of plant 3–4 cm, of spikes 1–1.5 mm. Alaska: Tanana Valley, Harding Lake. July 2001. Photographed by Heidi Solstad. Voucher in HbO. • 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).
