in Willkomm & Lange,
Worldwide, primarily in tropical and subtropical regions.
Selaginellaceae traditionally include only one genus of living plants, Selaginella (A. C. Jermy 1990b; R. M. Tryon and A. F. Tryon 1982). Some authors (O. Kuntze 1891–1898, vol. 2, pp. 824–827; W. Rothmaler 1944), however, have segregated other genera based on generic concepts established by A. Palisot de Beauvois (1805, pp. 95–114), who recognized four genera. A. F. Spring (1850) combined the four genera into the broadly defined genus Selaginella. Spring's generic delimitation has resulted in misinterpretations that created many nomenclatural problems and partly led to the continued recognition of only one genus. Nevertheless, species in Selaginella fall into at least three well-defined groups, all present in North America, that may be recognized as genera based on anatomy, embryology, morphology and arrangement of the leaves and sporophylls, and morphology and symmetry of the strobilus. North American Selaginellaceae, which represent only a small portion of the family, are treated here in Selaginella, pending a full revision of the family worldwide.
Species in the fossil genus Selaginellites Zeller, which dates to the Carboniferous period, presumably are congeneric with Selaginella. Among the fern allies, Selaginellaceae are related only distantly to the other lycopod families, Lycopodiaceae and Isoëtaceae (R. M. Tryon and A. F. Tryon 1982).
Genera 1, over 700 species (38 species in the flora).