250 HISTORY OP BRITISH FERNS. 



been met with only in a limited number of localities in 

 Ireland, Scotland, and the north of England. 



EQUISETUM VARIEGATTJM, Weber and Mohr. The Va- 

 riegated Bough Horsetail. 



This species is found on the banks of rivers and lakes, and 

 in sandy places near the sea. There is considerable variation 

 among the plants classed under this name, and met with in 

 these different localities, the differences appearing to be 

 permanent under cultivation, but we have not yet sufficient 

 evidence to treat them as distinct species. We, therefore, 

 include as varieties or forms of variegatum,'$\Q dwarf pro- 

 cumbent plant sometimes called JEJ. arenarium, and the tall 

 stout erect form which has been named E. Wilsoni. 



This is one of the species whose stems are all similar, and 

 almost quite unbranched. It extends by means of a widely 

 creeping underground stem, rooting in whorls like the other 

 species, and producing numerous above-ground stems, often 

 springing from joints in such close proximity, that they 

 appear in dense tufts. Though so numerously branched 

 just beneath or at the surface of the soil, it is not usual that 

 any branches are produced on the exposed part of the stems, 

 but this sometimes does occur, such branches not growing 

 in whorls, but springing singly from the joints, and having 



