Pumice moonwort (Botrychium pumicola) is a rare fern of southern Oregon and the Modoc Plateau in northern California. It pertains to the adder's-tongue family (Ophioglossaceae) which may be closely related to the whisk ferns (Psilotaceae). These two families together, according to recent research, share a common ancestor which appears to have diverged early on from the rest of the fern lineage; this probably explains the distinctive morphologies of the members of these two families.