Equisetaceae, the Horsetail Family 1. Equisetum laevigatum A. Br. E. kansanum J. H. Schaffner. A hybrid between E. hyemale and E. laevigatum is referred to as E. X ferrissii Clute. The hybrid produces sterile cones with abortive spores.
Reproduction is entirely vegetative by rhizomes and fragmentation of the stems.
The range of E. X ferrissii corresponds with that of E. hyemale in the northern plains.