Equisetaceae Michaux ex A.P. de Candolle.
A family with a single genus and about 15-20 species. Equisetaceae is an evolutionarily isolated group, which has been interpreted variably over time. The current consensus is that Equisetaceae be included as "ferns", but the basalmost group to be so considered. The profound morphological differences and ancient age of the lineage make its treatment as a separate class from the ferns equally or more compelling.
Ref: Christenhusz et al. (2019); Des Marais et al. (2003); Hauke (1993) In Flora of North America Editorial Committee (1993b); Hauke In Kramer & Green (1990); Lellinger (1985); Mickel (1979); PPG I (2016). Show full citations.