FARWELL: genus HIPPOCHAETE in north AMERICA 469 



HiPPOCHAETE PREALTA var. scabrcUa (Engelm.?) comb. nov. 



? Equisetum laevigatum var. scabrellum Engelm. in A. Br. Am. 

 Jour. Sci. 46: 87. 1843. 



? Equisetum hiemale var. texanum Milde; A. A. Eaton, Fern 

 Bull. 11: 108. 1903. 



Similar to the preceding variety but the sheaths are propor- 

 tionably broader and the teeth deciduous or persistent, indicating 

 a cross between H. laevigata and H. prealta, if these intermediate 

 forms are to be considered as the result of hybridization. I do 

 not know if this is Engelmann's variety or not but it agrees in 

 every particular with Eaton's description of Equisetum laevigatum 

 var. scabrellum in Fern. Bull. 11: 42. 1903. The stems of the 

 season have the general aspect that H. laevigatum would have if 

 its sheaths had persistent teeth; the stems of the preceding year 

 have the general markings of H. prealta. The anatomy is now 

 of the one species, now of the other. 

 Rochester, Mich., Farwell 3712}^, July 4, 1914. 



Hippochaete laevigata {A. Br.) comb. nov. 



Equisetum laevigatum A. Br. Am. Jour. Sci. 46: 87. 1843. 



This species in its typical form is well characterized by its 

 simple or branched, annual, stems, which are smooth, at least to 

 the touch, its rounded spikes, and campanulate sheaths with 

 caducous teeth. Those varieties which are intermediate between 

 this and other species generally will have rough stems and spikes 

 that are either obtuse or aplculate. It may be found In clear 

 sand or gravel, or a similar soil covered with a sparse growth of 

 grass and other vegetation and generally not far from water. 



It may be found in colonies by itself, or it may be associated 

 with H. prealta and Its variety affinis, H. variegata, and Equisetum 

 limosum. The vallecular bast divides the green parenchyma into 

 y-shaped divisions. Eaton restricted this species east of the 

 Mississippi to Ohio, Indiana, Illinois, and Wisconsin; but I have 

 found it In southeastern Michigan, where It is common, and on 

 the Keweenaw Peninsula, where it cannot be said to be scarce. 

 Probably it Is to be found throughout the state. The annual 

 stems begin their growth about the first of May, are fruiting in 

 June, and perish in July or August. New stems are appearing 

 continuously until the middle of the summer but all have perished 



