EQUISETUM SPOROPHYTE 325 



C. EQUISETINE^E 



EQUISETUM ARVENSE (The Common Horse- 

 Tail) 



THE SPOROPHYTE 



External Characters 



I. Observe with the naked eye the following external 

 characters in specimens of E. arvense, which is the com- 

 mon Horse-tail of corn-fields and road-sides : its green 

 vegetative shoots are to be found from early summer 

 onwards. The root-stock being a creeping one, and 

 underground, it cannot be removed from the soil with- 

 out injury by merely pulling it up : the specimens 

 should be carefully dug up, so that the several parts 

 may be seen in their natural position relatively to 

 one another. 



1. The external conformation of the axial struc- 

 tures or stems is the same whether they be creeping 

 and underground, or erect and aerial : they consist of 

 more or less elongated joints or internodes, marked off 

 from one another by nodes, which may be recognized 

 as the points of insertion of 



2. The leaf-sheaths, each of which surrounds the 

 base of the internode next above it, and splits at its 



