1 Vegetative leaves monomorphic, spirally arranged around the stems; leaves acuminate and with a white or translucent apical hair-tip (the hair-tip rarely lost); fertile branch tip only slightly differentiated from the sterile portions of the stems; rhizophores dorsal (initiated from the upper side of the stems), borne either along the stems or only from rhizome-like stems; rhizophores medium-fine, 0.2-0.45 mm in diameter; [subfamily Gymnogynoideae]

1 Vegetative leaves dimorphic, in 4 ranks, the ventral pair spreading laterally, the dorsal pair ascending, the pairs different in shape and/or size (anisophyllous); leaves acute, mucronate, lacking a white or translucent apical hair-tip; fertile branch tips strongly differentiated (into strobili) from the sterile portions of the stem; rhizophores either dorsal or ventral, borne along the stems; rhizophores either very fine or medium fine, 0.02-0.4 mm in diameter, or coarse, 1-3 mm in diameter.

..2 Rhizophores dorsal (initiated from the upper side of the stems); stems articulated with a swelling near each branching node; rhizophores 1-3 mm in diameter; [subfamily Gymnogynoideae]

..2 Rhizophores ventral (initiated from the lower side of the stems); stems not articulated; rhizophores 0.02-0.4 mm in diameter (except 2-3 mm in diameter in the non-native and apparently s. FL restricted D. willdenowii).

....3 Sporophylls dimorphic; megaspore surfaces tuberculate, papillate, or very finely reticulate; [non-native species used horticulturally and sparingly spreading or naturalizing]; [subfamily Lycopodioidoideae]

....3 Sporophylls monomorphic; megaspore surfaces reticulate; [native species; collectively widespread and common]; [subfamily Selaginelloideae; section Pallescentes]