248 
HISTORY OF BRITISH FERNS. 
The name Equisetum is compounded from equus, a 
horse, and seta , a hair or bristle; whence comes the 
English name of Horsetail,—a not inapt comparison with 
the barren stems of some of the species. 
Equisetum Telmateia, Ehrhart. 
The Great Horsetail; or Great Water Horsetail. 
(Plate XX. fig. 2.) 
This is one of those species in which the ordinary fertile 
and the barren stems are perfectly dissimilar*, the former 
being short and quite simple, the latter tall and compoundly 
branched. Occasionally a third sort of stem a kind of 
compromise between the two, is produced late in the season, 
reaching maturity about August, and bearing a very small 
proportion to the exclusively barren or fertile stems. They 
are smaller, though with longer joints ; have shorter, less 
spreading sheaths ; and bear catkins which are smaller than 
usual. This state of the plant has been attributed to 
drought; and seems to be one of those occasional and in¬ 
constant variations to which plants are liable, as they are 
influenced by the external circumstances of soil or climate, 
or the peculiarities of the seasons. 
The barren stems of this species are very stately objects 
