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| The Equisetum species (horsetails) of Britain and Ireland |
“Marsh Horsetail”.
The rhizomes often(?) bearing tubers. The shoots all green and alike vegetatively, the sterile and cone-bearing shoots emerging at the same time.
The main stems 10–60 cm high; 1–3 mm in diameter; erect, or decumbent; slightly rough; bearing whorls of slender branches at the nodes (usually, but often irregularly), or sparingly branched, the branches solitary and similar to the main stem, or simple; dying down in autumn. The main stem internodes not swollen; 4–8 grooved; grooves deep, with prominent ridges between. The main stem internodes with a central hollow; central hollow much much less than half the diameter of the internode (small, scarcely larger than the outer canals); endodermis comprising a single layer outside the ring of vascular bundles. The main stem sheaths green; 4–12 mm; loose; 4–8 toothed. The teeth one ribbed; triangular-subulate, blackish, with narrow, whitish-scarious margins; persistent (?). The primary branching symmetrical to asymmetrical (often irregular). The primary branches few to numerous; ascending to spreading; simple (spreading to sub-erect, often short). The primary branch internodes 4–5 grooved; 4–5 grooved. The primary branch sheaths 4 toothed (these short, appressed, black-tipped). The first branch internodes much shorter than the subtending sheaths. The primary branch internodes hollow. Stomata not sunken.
The cones 1–3 cm long; blunt. Spores released May to July.
Distribution. Europe, from Iceland and northern (not arctic) Russia to central Spain and northern Portugal, Sicily, Greece and the Caucasus, temperate Asia; and North America, from Newfoundland and Alaska to Connecticut and Oregon. Common throughout the British Isles, in bogs, fens, marshes and wet heaths, woods and meadows, ascending to nearly 1000 m.
Classification. Subgenus Equisetum; Section Aestivalia.
Illustrations. • E. palustre, fertile stem: Sowerby and Johnson, 1859. Equisetum palustre L. Fertile stem, with part of internode transverse section. From Sowerby and Johnson (1859). • E. palustre, variety: Sowerby and Johnson, 1859. Equisetum palustre L. var. polystachion, with detail of a primary stem sheath. From Sowerby and Johnson (1859). • E. palustre: Eng. Bot. 1892 (1886). • 10 British and Irish Equisetum species and hybrids: Sowerby and Johnson, 1863. 1701, Equisetum arvense L.; 1702, E. pratense Ehrh.; 1703, E. telmateia Ehrh.; 1704, E. sylvaticum L.; 1705, E. fluviatile L.; 1706, E. palustre L.; 1707, E. hyemale L.; 1708, E. x moorei Newman; 1709, E. x trachyodon A.Br.; 1710, E. variegatum Schleich. ex Web. & Mohr; 1711, E.variegatum var. wilsonii (Newm.) Milde. From Sowerby and Johnson (1863). • E. palustre: details of fertile stem, sporangiophore and spores. Equisetum palustre L. a-e, fertile stem (a, internode; b, sheaths on main stem; c, branch sheaths; d and e, cone with sporangiophores; g, detail of a sporangiophore, inverted to show 7 dehisced sporangia; h, a spore with elaters wrapped around it (above) and spread. From De Candolle (1835).
We advise against extracting comparative information from the descriptions. This is much more easily achieved using the DELTA data files or the interactive key, which allows access to the character list, illustrations, full and partial descriptions, diagnostic descriptions, differences and similarities between taxa, lists of taxa exhibiting or lacking specified attributes, and distributions of character states within any set of taxa. See also Guidelines for using data taken from Web publications.
Cite this publication as: ‘Watson, L., and Dallwitz, M.J. 2004 onwards. The Equisetum species (horsetails) of Britain and Ireland. Version: 5th August 2019. delta-intkey.com’.
