? 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.