The EquisetumSpecies (Horsetails) of the British Isles
Dutch Rush, Scouring Rush.
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; persisting through the winter. The main stem internodes somewhat 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 (2/3 or more); endodermis comprising two layers, one outside and the other inside the ring of vascular bundles. The main stem sheaths soon whitish, black-banded at top and bottom; about as broad as long (3–9 mm); appressed; 10–30 toothed (as many as the grooves). The teeth caducous (leaving the sheaths with crenulate upper edges). Stomata sunken.
The cones 8–15 cm long; apiculate. Spores released July to August.
Distribution. Europe, from Iceland and northern (not arctic) Russia to central Spain, Corsica, northern Italy, Crete and the Caucasus; northern and central Asia; and western North America south to California and New Mexico. In Britain, from Somerset and Kent to Sutherland, very rare in southern England and Wales, scattered over Ireland. In shady moist places, to about 550 m.
Classification. Subgenus Hippochaete.
Illustrations. • E. hyemale (Sowerby and Johnson). • 10 British Equisetum species and hybrids (Sowerby and Johnson). • E. hyemale: details of a stoma.
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’.