EQUISETUM. 255 



been meet with only in a limited number of localities in 

 Ireland, Scotland, and the north of England. 



Equisetum arvense, Linnwus. 

 The Corn-field Horsetail. 



This is the most common of the species, and in many 

 places is an injurious weed, very difficult to eradicate. It 

 occurs here and there, almost everywhere, in fields and 

 waste places, especially where the soil is inclined to be 

 sandy, and more abundant in moist than in dry places. It 

 has long, creeping, underground stems, which are a good 

 deal branched, and are cylindrical and jointed in the same 

 way as the stems which rise above ground. At the joints 

 they throw out whorls of tough, branching, fibrous roots. 

 The aerial stems are of two kinds, the one. simple and 

 bearing the fructification only, the other branched and 

 perfectly barren. 



The fertile stems are quite without branches, and grow 

 up early in spring, arriving at maturity and perishing 

 long before the barren ones have completed their growth. 

 They reach maturity in April and May. The stems vary 

 from three to eight or ten inches in height. They are 

 hollow, succulent when fresh, and of a light brown colour, 



