Elatinaceae

Tiny aquatic non-woody (herbaceous) annuals with no hairs; typically growing in shallow water and emerging when water levels drop. Stems upright to creeping, with longitudinal air spaces, often branching and often rooting at the nodes, sometimes forming small mats.

Leaves opposite, linear to narrowly oval, small, not more than 8 mm long, with smooth edges.

Flowers tiny, usually solitary, in leaf axils, each flower producing both pollen and seeds. Sepals, petals and stamens each 2-4. Carpels 2-4, forming 1 pistil; ovary located above point of attachment of other flower parts (superior); styles 2-4. Fruit a many-seeded thin-walled capsule with 2-4 chambers. Surface of seeds with ridges that outline very tiny shallow pits; these patterns are useful for identification.