Phylogenetic scheme of pteridophytes at the (sub)family and higher taxonomic levels. The family or deeper relationships follow PPG I (2016). The inter-subfamily relationships follow Field et al. (2016) for Lycopodiaceae, Kim and Kim (2018) for Ophioglossaceae, Ebihara et al. (2006) for Hymenophyllaceae, Schuettpelz et al. (2007) for Pteridaceae, Liu et al. (2016) for Dryopteridaceae, Schneider et al. (2004) for Polypodiaceae, Almeida et al. (2016) for Thelypteridaceae, and de Gasper et al. (2017) for Blechnaceae.