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

Equisetum scirpoides Michx.

English: Dwarf scouring rush,

French: Prêle faux-scirpe.

Equisetaceae, Horsetail or Scouring rush family.

Published in Fl. Bor.-Amer. 2: 281. 1803.

Type: Described from Canada.

Synonymy. Hippochaete scirpoides (Michx.) Farw.

Vegetative morphology. Plants 2.5–15(–28) cm high; perennial herbs; not caespitose (usually); jointed fertile stems with pigmentation. Only fibrous roots present. Roots black (or very dark brown). Ground level or underground stems horizontal, or vertical; rhizomatous (usually), or stoloniferous; elongate; 0.4–0.7 mm wide (at the base of aerial stems). Ground level or underground stems scales present; 3(–4); dull black; (1–)2–2.5 mm long (dull black); glabrous. Aerial stems developed; erect, or prostrate; conspicuously jointed with nodes covered by whorls of tiny leaf teeth fused for part of their length into sheaths that are tipped with teeth (stems persist less than a year); filiform (wiry). Aerial stem ridges 6(–8); twice as many ridges as there are leaf teeth. Leaves absent or leaf teeth; leaf teeth (in whorls distributed along the stem). Leaf teeth persistence persistent (on unbranched stems that persist more than one year). Leaf teeth 0.5–1.5 mm. Leaf teeth 0.5–0.8 mm. Leaf teeth dull and black (with transparent margins, apices acuminate on young leaf teeth; often long enough to twist on older leaf teeth).

Reproductive morphology. Plants with sporangia, or vegetative leaves without obvious spore-bearing organs. Sporangia in terminal cone-like structures (on stems with chlorophyll). Aerial stems squarish in cross-section.

Chromosome information. 2n = 216 (and ca. 200).

2n = 216. Löve in Bir (1960, Iceland); Löve and Löve (1961c, Iceland); Hauke (1993, Fl. N. Amer. 2, secondary reference), and some more southern counts.

Ploidy levels recorded 2x.

Ecology and habitat. Substrates: ridges; moderately well-drained areas; rocks, gravel; with low organic content. Limited to the most favourable habitats in the Canadian Arctic Archipelago (Porsild 1957).

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. Rare. Low Arctic. Arctic islands: Baffin, Banks, King William, Southampton (Coats and Nottingham).

Northern hemisphere distribution. Circumpolar, or circumboreal. 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, West Greenland.

General notes. Porsild (1957) suggested that this species is probably always sterile in the Canadian Arctic Islands, but fertile specimens have been collected on Southampton, Coats, and Baffin Islands. Cones may mature in summer or they may overwinter and shed spores in the spring.

A diagnostic difference distinguishing this species from E. variegatum is that the base of the plant is strongly papillose (and dull), whereas it is almost smooth and shiny in E. variegatum. Very often the stems of E. scirpoides are papillose along the ridges, but this may also be observed in E. variegatum. The young or undamaged "teeth" have attenuated tips that are sometimes sufficiently long to twist, especially at the uppermost node of a stem branch. The stems are perennial and firm in E. scirpoides, whereas they are annual and soft in E. arvense.

Illustrations. • Habitat: Cape Dorset. Plant growing in roadside gravel. Nunavut, Baffin Island, Cape Dorset. August, 2005. Aiken and A. Archambault 05–085. CAN 56956. • Herbarium specimen. Plants with thin, wiry stems and cones about 0.5 cm long at the tips of some branches. Coats Island, Hudson Bay. CAN 393561. • Close-up of cone. Cone that is beginning to dehisce from the base. Lower stems show the limited number of teeth at each node. CAN 393561. • Close-up of node and cone. Node with two teeth showing and two ridges in the lower internode. Cone about 2 mm high. • Close-up of base of plant. Underground rhizomes orange-brown with prominent ridges and nodes with dull black scales. • Close-up of aerial stem. Base of aerial stem with four leaf teeth visible at the nodes. The arrow (A) points to the double ridge ending in a single tooth, characteristic of this taxon. • Contrasting stems. Equisetum variegatum stems (left) that usually have more stem ridges and are larger in diameter than E. scirpoides (right). Also note the difference in the tips of the leaf teeth. Drawing by Mrs. S. Bergh and Mrs. L. Barstad based on a collection from Svalbard, Sørkapp Land, Sunder Kistefjell. 21 August, 1920. J. Lid. 112. O 205227. With permission of the Botanical Museum, University of Oslo, Norway. • 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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