FARWELL: genus HIPPOCHAETE in north AMERICA 467 



Hippochaete scirpoides (Michx.) comb. nov. 



Eqiiisetiim scirpoides Michx. Fl. Bor.-Am. 2: 281. 1803. 



Our smallest species, forming dense mats along old logs and 

 stumps in open fields, cedar swamps, etc. Well characterized by 

 its three leaves and ridges, the latter so deeply and broadly con- 

 cave that the stem apparently is 6-ridged. 

 Keweenaw Peninsula, Mich., Farwell 212, May 30, 1885. This 



has much the same range as H. variegata but extends about 2° 



further south. 



Hippochaete prealta (Raf.) comb. nov. 



Equisetum prealtum Raf. Fl. Ludovic. 13. 1817. 



Equisetiim robustum A. Br. Am. Jour. Sci. 46, 88. 1843. 



Equisetum robustum var. minus Engelm. in A. Br. Am. Jour. 

 Sci. 46, 88. 1843. 



Equisetum hyemale var. Driimmondi Milde, Mon. Equit. 593. 

 1865 (?). 



Equisetum hiemale var. robustum A. A. Eaton, Fern Bull. 11: 

 112. 1903. 



Equisetum hiemale var. californicum Milde; A.. A. Eaton, Fern 

 Bull. 11: 113. 1903, as to the plants with rounded ridges. 



Equisetum hyemale var. prealtum (Raf.) Clute, Fern Bull. 16: 18. 

 1908. 



This is our largest and most widely spread species and probably 

 our most common one. It is well characterized by its cylindrical, 

 tight sheaths, which are as broad as long or sometimes a little 

 broader or narrower than long, its persistent teeth, and very 

 numerous, rounded ridges. It may be found on sand banks, in 

 poor soil, in swamps and bogs; generally near water. Mr. C. K. 

 Dodge has collected it near Port Huron, Mich., and near Sarnia, 

 Ontario. 

 Keweenaw Peninsula, Mich., Farwell 20Qy2, May 30, 1885; 5^2, 



Aug. 29, 1887. Rochester, Mich., Farwell 2g'j5, Aug. 4, 1912; 



36g6 and 3710, June 28. 1914; 3722, July 19, 1914; 3922 and 



3927, October 25, 1914. Parkedale Farm, Mich., Farwell 



3988 }/2, June 20, 191 5. May be found from the Atlantic to 



the Pacific but rare east of the Mississippi basin. 



Hippochaete prealta var. affinis (Engelm.) comb. nov. 



Equisetum robustum var. affine Engelm, in A. Br. Am. Jour. 

 Sci. 46: 88. 1843. 



