The genus has a large number of species. The PPG I classification suggested that there were about 125 species;[1] as of February 2020[update], the Checklist of Ferns and Lycophytes of the World listed 143.[2]
^ abcPPG I (2016), "A community-derived classification for extant lycophytes and ferns", Journal of Systematics and Evolution, 54 (6): 563–603, doi:10.1111/jse.12229, S2CID39980610