Isotopic and molecular data support mixotrophy in Ophioglossum at the sporophytic stage.

Most land plants, from liverworts to angiosperms, form mutualistic arbuscular mycorrhizal (AM) symbioses with Glomeromycotina (Smith & Read, 2008). Plants gain essential mineral nutrients from their mycorrhizal partners in exchange for photosynthesis-derived carbon (Smith & Read, 2008). Nonetheless, mutualisms, including mycorrhizal ones, allow exploitation by a third lineage (cheating strategies; Bronstein, 2001; West et al., 2007).