Monographs Details: Hippochaete prealta var. scabrella (Engelm.) Farw.
Authority: Farwell, Oliver A. 1916. The genus Hippochaete in North America, north of Mexico. Mem. New York Bot. Gard. 6: 461-472.

? Equisetum laevigatum var. scabrellum Engelm. in A. Be. 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 proportionably 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 1/2, July 4, 1914.