Marsileaceae - Water-clovers and pillworts
Photo: P. Ballings
Description of the family
Small aquatic or semi-aquatic ferns, rooting in mud, with widely creeping, dichotomously branched rhizomes of indefinite growth. Fronds numerous, approximate to widely spaced, 1-pinnate with 2 pinna pairs in a clover-shaped cluster at the apex of a long, slender, cylindrical petiole or lamina lacking; veins dichotomously branched, anastomosing. Sporangia in closed sporocarps; sporocarps inserted on short stalks (pedicles)on the stipe (usually at the base), heterosporus.
Worldwide: 3 genera and c. 75 species worldwide, in arm-temperate and (sub)tropical regions.