Equisetum variegatum var. Nelsoni A. A. Eaton, Fern. Bull. 12: 41. 1904.
Intermediate between H. laevigata and H. hyemails var. Jesupi but more like the latter in appearance than the former. The rounded ridges and annual stems, however, place it more appropriately in the section Ambigua than in the Euhippochaete. The parenchyma is frequently divided by the vallecular bast but not regularly so. The sheaths in dried plants are liable to be slightly ampliated. It has been collected in New York, Michigan, and Illinois.