The EquisetumSpecies (Horsetails) of the British Isles
E. occidentale (Hy) Coste.
The rhizomes not tuberous. The shoots all green and alike vegetatively, the sterile and cone-bearing shoots emerging at the same time.
The main stems 30–100 cm high; 4–6 mm in diameter; erect; dull green (glaucous); very rough (on the ridges, these with two regular rows of tubercles); simple; dying down in autumn (at least, to near the base). The main stem internodes not swollen; 10–30 grooved; grooves moderately deep. The main stem internodes with a central hollow; central hollow about half the diameter of the internode to more than half the diameter of the internode (about 3/5). The main stem sheaths soon whitish, black-banded at top and bottom; longer than broad; somewhat loose; 10–30 toothed (as many teeth as grooves). The teeth persistent (at least, more so than in E. hyemale, dark brown, truncate). Stomata sunken.
The cones 8–15 cm long; apiculate. Spores abortive.
Distribution. Western and central Europe, the detailed distribution uncertain owing to problems of identification. In the British Isles, known from maritime dunes and banks in Wicklow and Wexford, and from one locality in Surrey.
Classification. Subgenus Hippochaete; = E. hyemale x E. ramosissimum.
Illustrations. • E. × moorei (Sowerby and Johnson). • 10 British Equisetum species and hybrids (Sowerby and Johnson).
To view the illustrations with detailed captions, go to the interactive key. This also offers 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.
Cite this publication as: ‘Watson, L., and Dallwitz, M.J. 2004 onwards. The Equisetum species (horsetails) of the British Isles. Version: 21st June 2009. http://delta-intkey.com’.