Equisetum variegatum Schleicher ex F. Weber & D. Mohr
Variegated scouring rush, prêle panachée.
Equisetaceae, horsetail family.
Bot. Taschenbuch 60; 447. 1807.
Equisetum variegatum var. anceps Milde
Plants perennial herbs; tufted, with ascending, freely branched, rather stiff, straight stems that persist more than one year; less than 15 cm high (Arctic); 6–20(–48) cm high (further south). Roots black (or very dark brown). Ground-level or under-ground stems horizontal; rhizomatous, or stoloniferous; compact; 0.5–1.5 mm wide. Scales present; 3–8(–12); glabrous. Aerial stems prostrate (in tiny high Arctic plants), or erect (in more robust specimens from warmer climates); conspicuously jointed with nodes covered by whorls of tiny leaves fused for part of their length into sheaths that are tipped with teeth; filiform (in tiny Arctic plants that look wiry and like E. scirpoides), or not filiform (usually); circular or oval in cross-section; with 3–8(–12) ridges (the same number as that of the sheath teeth at each node); glabrous. Leaves distributed along the stems; whorled (on unbranched stems that persist more than one year); evergreen, or marcescent. Petioles absent. Leaf bases truncate (into a fused sheath). Blades 1–3 mm long; 0.5–1.5 mm wide; appressed to the stem; membranous (often black at the base and with prominent white margins); straight (erect); lanceolate (broadly), or triangular; flat; with parallel veins, or appearing single-veined, or with inconspicuous veins; adaxial surface glabrous. Blades abaxial surface glabrous. Leaf apices acuminate, or acute. Plants asexual, or reproducing by spores borne in sporangia. Sporangia in terminal cone-like structures (Cones have a pointed apex and mature late summer or overwinter and shed spores in spring).
Chromosome information. 2n = 216.
Distribution. Circumpolar. Arctic, or alpine. Range in the Canadian Arctic Archipelago widespread. Arctic Islands: Baffin, Ellesmere, Axel Heiberg, Parry Islands, Conrwallis, Banks, Victoria, Prince of Wales, Somerset, King William.
Ecology and habitat. Substrates, wet meadows, around the margins of ponds, marshes, along streams, river terraces; imperfectly drained moist areas (or wet); calcareous; sand, clay, moss; with low organic content.
Notes. Arctic floras have traditionally indicated that this species has 6–8 sheath teeth at each node which distinguishes it from E. scirpoides that has 3–4 sheath teeth that is twice as many teeth as stem ridges. Hauke (1993) indicates that E. variegatum may have 3–8(-14) ridges to the stem and as many teeth to the sheaths as there are ridges. (The number of ridges can be determined by cutting cross sections of the stem). Thus, E. variegatum plants may have 3–14 sheath teeth at each node. This has resulted in some specimens of E. variegatum being incorrectly assigned to E. scirpoides that Hauke (1993) indicates has twice as many ridges as sheath teeth, usually 3 but rarely four. The subspecies that occurs in the Arctic Archipelago is subsp. variegatum. Subsp. alaskanium also occurs in North America and is distinguised from subsp. variegatum on sheath teeth characters. Sheath teeth, erect, with prominent white margins subsp. variegatum; sheath teeth incurved, with obscure margins or all black, subsp. alaskanum.
Illustrations. • Plants in habitat. Plants growing in silt patch near a pond, the bright green plants in the foreground are abundant, N.W.T., Banks Island, Sachs Harbour. July 24, 1981, Gillett 18790. • Close-up of plants in habitat. Abundant plants growing on silt patch near pond, N.W.T., Banks Island, Sachs Harbour. July 24, 1981, J.M. Gillett 18790. CAN. • Close-up of plants. The tallest stem terminates with a young cone. Note stem joints with two leaf teeth visible. Plants growing on a silt patch near a pond. N.W.T., Banks Island, Sachs Harbour, July 24, 1981, Gillett 18790. CAN. • Close up of sterile stem. Stems with short green spreading branches and appressed teeth with brown margins. Banks Island, Sachs Harbour, 14 July, 1999. Susan Aiken 99–073. CAN. • Close-up of fertile stem. Close-up of young green cone on a green fetile stem. Banks Island, Sachs Harbour, 14 July, 1999. Susan Aiken 99–073. CAN. • Close-up of cone. Close-up of young green cone and sheath teeth with brown margins. Banks Island, Sachs Harbour, 14 July, 1999. Susan Aiken 99–073. CAN. • Contrasting stems. Left. E. vagietatum stems that usually have more stem ridges and are larger in diameter than E. scirpoides, right. Drawing by Mrs S. Bergh and Mrs L. Barstad based on a collection from Svalbard, Sørkapp Land, Sunder Kistefjell 21 Aug. 1920. J. Lid. 112. O 205227 With permission of the Botanical Museum University of Oslo, Norway. • Arctic Island Distribution.
Cite this publication as: S.G. Aiken, M.C. LeBlanc, and M.J. Dallwitz 2000 onwards. Pteridophytes of the Canadian Arctic Archipelago: Descriptions, Illustrations, Identification, and Information Retrieval.’ Version: 23rd February 2001. http://www.mun.ca/biology/delta/arcticf/’. Dallwitz (1980), Dallwitz, Paine and Zurcher (1993, 1995, 2000) , and Aiken, Dallwitz et al. (1999) should also be cited (see References).
