Marsileaceae

An aquatic or wetland fern whose fronds look nothing like a typical fern, instead resembling a four-leaf clover floating or standing above the mud on a long thin stalk; spores form inside hard, bean-like capsules at the base of the plant rather than in visible sori on the leaf.

As a true fern this family has no flowers or seeds — its four-leaflet, clover-like fronds are so unlike a typical fern that it is easily mistaken for a flowering plant at a glance.

To check whether a plant belongs to Marsileaceae, compare the leaf arrangement, leaf type, flower symmetry, fruit type, and one distinctive marker together. A single feature can mislead; the family pattern is the combination.