-SCOURING-RUSH," OR "HORSETAIL." 



Equisetum arvense. 



PTERIDOPHYTES; EQUISETALES; EQUISETINE^E. 



PRELIMINARY. 



THIS plant is selected as a representative of a subdi- 

 vision of the Pteridophytes, the Equisetales, in which there 

 are about twenty-five living species, all belonging to one 

 genus. Other species may be selected for study, but 

 the one named will be found most often in many localities. 

 It grows on shady hillsides, along railway tracks, and 

 sometimes in open fields. It may be found along the 

 banks of ponds and streams, but in such places other 

 species of Equisetum are more likely to be found. 



The pale reddish-yellow spore-bearing branches appear 

 early in the spring, usually the latter part of March 

 or April. They are straight unbranched shoots, from 

 three to twelve inches in height, and bear cone-like 

 structures at their tips. Near these achlorous shoots 

 and arising from the same underground stems will 

 be seen the branched green shoots. These become 

 much more prominent as the spore-bearing shoots dis- 

 appear. In other species than Equisetum arvense the 

 spores are borne by single tall unbranched green shoots. 



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