The Equisetum Species (Horsetails) of the British Isles
This data set is generated from a DELTA database (Dallwitz 1980; Dallwitz, Paine, and Zurcher 1993). It comprises descriptions of the species and hybrids, illustrated mainly from Sowerby and Johnson (1859 and 1863), with a file of source references and hints on using the program Intkey for interactive identification and information retrieval.
The descriptive content comprises data obtained mainly from Bentham and Hooker (1945 edition) and Clapham, Tutin and Warburg (1962), cross-referenced with Stace (1997). The nomenclature and classification are aligned with the Hassler and Swale’s world species list (2003), with the old Sections Aestivalia, Subvernalia and Vernalia superimposed on Subgenus Equisetum.