Hippochaete praealta var. affinis (Engelmann) Farwell

Hippochaete praealta var. affinis (Engelmann) Farwell is a synonym sensu Christenhusz et al., 2019 of:

Equisetum hyemale subsp. affine (Engelmann) Calder & Roy L. Taylor, an accepted subspecies name sensu FNA Ed. Comm., 1993.