Semiaquatic ferns grown in water for their neat, clover-like floating leaves grouped mostly in fours. Rhizome creeping, usually branched. Sterile fronds threadlike or with 2 or 4 leaves at the apex. Sori in a thick-walled fruiting structure (sporocarp).

The 2-leaved Regnellidium diphyllum Lindman, Latex Fern, from Brazil and Argentina is sometimes grown as an aquarium plant: the stem releases a white latex when broken.

3 genera, c. 70 species world-wide, mostly tropics (2 genera with 8 species in Australia).

2 and 4-leaved fronds floating on water surface.

Johnson (1986).

Source: Spencer, R. (1995). Marsileaceae. In: Spencer, R.. Horticultural Flora of South-eastern Australia. Volume 1, Ferns, conifers & their allies. The identification of garden and cultivated plants. University of New South Wales Press.