- China to India A molecular phylogenetic analysis in 2011 suggested that the four Onocleacae genera are so closely related that they could be included under the single genus Onoclea. A possible phylogenic relationship between Onocleaceae species (line lengths are not significant) is shown below. The Pteridophyte Phylogeny Group classification of 2016 (PPG I) maintained the four genera. References Polypodiales Fern families