The EquisetumSpecies (Horsetails) of the British Isles
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 50–75 cm high; greyish green; very rough to slightly rough (with scattered tubercles); bearing whorls of slender branches at the nodes (at least on their lower halves); persisting through the winter. The main stem internodes not swollen; 8–20 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 (1/2 to 2/3); endodermis comprising two layers, one outside and the other inside the ring of vascular bundles. The main stem sheaths green at first, then brown with a black band at the bottom; about 8 mm long. The teeth black, with narrow white margins and a hairlike apex; persistent. The primary branches numerous. The first branch internodes much shorter than the subtending sheaths (about a third its length). The primary branch internodes hollow. Stomata sunken.
The cones 0.6–1.2 cm long; apiculate. Spores released May to August.
Comments. The available descriptions are poor.
Distribution. Europe from Loire, southern Bavaria and central Russia southwards, and in isolated localities in Brittany, the Netherlands, and northern Germany; Asia, Africa and America. In Britain, first found on a grassy stream bank near Boston (S. Lincolnshire) in 1947.
Classification. Subgenus Hippochaete.
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: 7th March 2015. http://delta-intkey.com’.