Within the family Lycopodiaceae, Phlegmariurus is placed in the subfamily Huperzioideae. A phylogenetic study in 2016, employing both molecular and morphological data, concluded that either a one-genus or a three-genus division of the subfamily produced monophyletic taxa. The authors preferred the three-genus division, recognizing Huperzia, Phlegmariurus and Phylloglossum. Their preferred hypothesis for the relationships of the three genera was:[4]
The majority of the species formerly placed in a broadly defined Huperzia belong in Phlegmariurus.[4] However, the genera are difficult to separate morphologically, and others have preferred the one-genus division of the subfamily.[1]
Species
As of June 2024[update], the Checklist of Ferns and Lycophytes of the World accepted over 300 species:[1]
^PPG 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
^ abField, Ashley R.; Testo, Weston; Bostock, Peter D.; Holtum, Joseph A. M. & Waycott, Michelle (2016), "Molecular phylogenetics and the morphology of the Lycopodiaceae subfamily Huperzioideae supports three genera: Huperzia, Phlegmariurus and Phylloglossum", Molecular Phylogenetics and Evolution, 94 (Pt B): 635–657, doi:10.1016/j.ympev.2015.09.024, PMID26493224