Greek ophis, snake, +glossa, tongue, in reference to the fertile spike resembling a snake's
tongue.

Plants small, herbaceous, terrestrial. Rhizomes erect, mostly underground, short, fleshy, roots fleshy with few branches, usually with proliferations producing clones. Sterile blades usually small, simple, without midvein, elliptic-lanceolate to ovate, glabrous. Veins reticulate. Fertile spikes linear, stalked, usually unbranched, arising at bases of sterile blades or tips of stems, with 2 vertical rows of large sporangia opening by horizontal slits, containing thousands of spores.

Identification of species in this primitive genus of ferns is often difficult because of the small number of characters available. These small terrestrial plants usually grow in open area and are often overlooked because they are inconspicuous and do not resemble typical ferns. The fronds of most fern families grow by circinate vernation, but the fronds of Ophioglossaceae do not form crosiers. One or more fronds usually emerge each year, and sometimes years are skipped.

A genus of about twenty-five to thirty species worldwide, found in both temperate and tropical areas. Represented in Hawai 'i by three probably indigenous species.