In the molecular phylogenetic classification of Smith et al. in 2006, Ophioglossales, in its present circumscription, was placed in the class Psilotopsida, along with the order Psilotales. The linear sequence of Christenhusz et al. (2011), intended for compatibility with the classification of Chase and Reveal (2009), which placed all land plants in Equisetopsida, made it a member of subclass Ophioglossidae, equivalent to Smith's Psilotopsida. This approach has subsequently been followed in the classifications of Christenhusz and Chase (2014) and PPG I (2016).