A genus of about 41 species, nearly cosmopolitan, primarily tropical. CircumscIption follows PPG I (2016).
ID notes: Ophioglossum is distinctly "unfernlike", with a single elliptical or ovate leaf blade (the trophophore) and a narrow, tonguelike sporangium-bearing sporophore branching from near the base of the trophophore blade. The sporophore bears the large sporangia in two rows. The netlike (interconnecting and anastomosing) venation requires strong backlight or chemical 'clearing' of the leaf to see well.