II, respectively. Former families became subfamilies (see the table above). The former Hemidictyaceae were included in the Asplenioideae, and the Onocleaceae in the Blechnoideae. In the new Polypodiaceae, Didymochlaena was placed in its own subfamily, Didymochlaenoideae. The PPG I classification (2016) used a process intermediate between the two previous approaches, by introducing a new rank, that of suborder, and organising 26 families (in some cases very narrowly circumscribed) into six suborders, largely returning to the families set out by Christenhusz et al. in 2011. In lieu of the expansion of Aspleniaceae and Polypodiaceae, eupolypods I and II were recognized and named as suborders: Saccolomatineae includes the single family Saccolomataceae. Lindsaeinae corresponds to the Lindseaceae of Smith et al., and includes the Cystodiaceae, Lindsaeaceae, and Lonchitidaceae. It is probably not monophyletic. Pteridineae includes the single family Pteridaceae. Dennstaedtiineae includes the single family Dennstaedtiaceae. Aspleniinae (formerly eupolypods I) includes the families Cystopteridaceae, Rhachidosoraceae, Diplaziopsidaceae, Desmophlebiaceae (containing only Desmophlebium), Hemidictyaceae, Aspleniaceae, Woodsiaceae, Onocleaceae, Blechnaceae, Athyriaceae, and Thelypteridaceae. Polypodiineae (formerly eupolypods II) includes the families Didymochlaenaceae (containing only Didymochlaena), Hypodematiaceae, Dryopteridaceae, Lomariopsidaceae, Nephrolepidaceae, Tectariaceae, Oleandraceae, Davalliaceae, and Polypodiaceae. Phylogeny Obsolete families Now-obsolete families of Polypodiales include: Drynariaceae - now in Polypodiaceae Grammitidaceae - now in Polypodiaceae Gymnogrammitidaceae - now in Polypodiaceae Loxogrammaceae - now in Polypodiaceae Platyceriaceae - now in Polypodiaceae Pleursoriopsidaceae - now in Polypodiaceae Vittariaceae - now in Pteridaceae Evolution Polypodiales may be regarded as one of the most evolutionarily advanced orders of monilophytes (ferns), based on recent genetic analysis. They arose and diversified about 100 million years ago, probably subsequent to the diversification of the angiosperms. References Bibliography , in Eric Schuettpelz. The evolution and diversification of epiphytic ferns. PhD Thesis Duke University 2007 Michael Hassler and Brian Swale. Checklist of Ferns and Fern Allies 2001 Australian National Botanic Gardens. A classification of the ferns and their allies Fern orders