THE GENUS HIPPOCHAETE IN NORTH AMERICA, 

 NORTH OF MEXICO 



Oliver Atkins Farwell 



Parke, Davis and Company, Detroit 



My attention was specifically drawn to these plants through 

 the monograph of the genus Equisetum by Mr. A. A. Eaton, which 

 appeared serially in the Fern Bulletin, and in which the exclusion of 

 E. laevigatum and E. robustum from Michigan was so opposed to 

 my field studies of these species, as I understood them, that I 

 concluded to give the subject further and more careful attention 

 in order to confirm my earlier views or to reject them. Mr. Eaton, 

 it is true, credited E. robustum to Sarnia, Michigan, but Sarnia is 

 in Ontario, Canada. These two species are unquestionably found 

 in Michigan. 



The following notes are based primarily on field studies, supple- 

 mented by studies of material distributed by Eaton and of that 

 in the herbarium of Parke, Davis & Co. 



Mr. Eaton said there were no true varieties, with perhaps the 

 exception of E. arvense var. boreale, in the genus Equisetum; and 

 then listed a large number, many of them new, but specifically 

 made no claims for their constancy. A goodly number of these 

 so-called varieties are based entirely on an injury to the individual 

 plant, and therefore are no more deserving from a systematic 

 point of view, of a special name and the dignity which is always 

 conferred by the elevation of a form to one of the named nomen- 

 clatorial categories, than is, in the higher plants, a willow stump 

 that has sent out innumerable branches to prolong its existence; 

 or if it pleases you to have the subject matter brought a little 

 nearer home, than is a man with an artificial limb to be ranked 

 as a new species in the genus Homo. All these so-called varieties 

 may be produced at will from the same evergreen stalk. The 

 apex of a normal evergreen stem may be broken off and labeled 

 under its specific name; the following year another section, now 

 with long branches, may be broken off and labeled var. ramigerum; 



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