THE HORSETAILS. 67 



The sporophylls do not draw apart at maturity, as in 

 other species ; but this is of no consequence, since the 

 spores will not germinate. 



The range of Equisetum lit tor ale is given as from New 

 Jersey and Pennsylvania to Minnesota and northward. 

 It is only occasionally found, but, where present at all, 

 often occurs in great abundance notwithstanding the 

 abortive spores, since it spreads rapidly by means of its 

 rootstocks. Mr. Eaton notes that along the lower Mer- 

 rimac River the plant is so abundant as to be cut for hay 

 under the name of " joint-grass." It prefers a drier location 

 than does Equisetum fluviatile, but both may be found 

 together. According to Mr. Eaton the two species may 

 readily be distinguished in the field by a section of the 

 stem just below the joints. In stems of Equisetum litto- 

 rale the cross-section presents a star-like opening, while 

 that of Equisetum fluviatile is larger and circular. In 

 Equisetum littorale the vallecular canals are always pres- 

 ent, but they are absent in Equisetum fluviatile except in 

 large or old stems. It is easily distinguished from Equi- 

 setum fluviatile, however, by the fact that the sheaths 

 are never so closely appressed to the stem, the grooves 

 of the stem are fewer and deeper, and the central hollow 

 is not so large. The shore horsetail is also found in the 

 Old World, extending from England to France, Austria, 

 Russia, and Scandinavia. 



