Older treatments have recognized segregate families within Ophioglossales such as Botrychiaceae for the moonworts and grape ferns and Helminthostachyaceae for " Helminthostachys ", but all modern treatments combine all members of the order into the single family Ophioglossaceae.
12.
The class should not be confused with the current use of the name Psilotopsida, which refers to a class of living ferns, containing only Psilotaceae ( whisk-ferns ) and Ophioglossaceae ( moon-worts and adder's-tongue ferns ).
13.
"' Ophioglossaceae "', the adder's-tongue family, is a family of ferns ( though some studies have instead suggested a closer relationship to angiosperms ), currently thought to be most closely related to Psilotaceae, the two together comprising the class Psilotopsida as the sibling group to the rest of the ferns.
