The ascocarps of most species in the family Geoglossaceae are terrestrial and are generally small, dark in color, and club-shaped with a height of 2–8 cm.

[5] Early molecular evidence using ribosomal DNA[6][7][8] suggested that Geoglossaceae sensu lato was not a monophyletic group, and that the hyaline spored genera (e.g. Leotia, Microglossum, and Spathularia) were not allied within the same clade as the darker-spored genera (Geoglossum and Trichoglossum).

Schoch et al.,[9] using a six-gene phylogeny including ribosomal DNA and protein-coding genes, found support for the establishment of a new class (Geoglossomycetes), containing the genera Geoglossum, Sarcoleotia, and Trichoglossum.

Further molecular research resulted in the addition of Nothomitra (previously treated as a relative or synonym of Microglossum) to the group in 2011.

[4] Several species in the genus Neolecta have similar morphology and are also known by the common name of "earth tongues", but they are members of the quite distantly related Taphrinomycotina, an entirely different subdivision of the Ascomycota.