Equisetum × mackaii (Newman) Brichan
Family: Equisetaceae
Hybrid Horsetail
[Equisetum x trachyodon ]
Images
not available
From Flora of Indiana (1940) by Charles C. Deam

My only specimens are from Pokagon State Park from the wet, sandy shore of the east side of Lake James and from the east side of Crooked Lake, Noble County.