Diversity:  Submersed marine herbs growing wholly submerged at depths of up to 50 m.  Three genera with about 18 species.

Distribution:  Worldwide and limited to sea coasts of subtropical to subarctic areas, of major importance, in terms of both ecology and economics, as primary producers in coastal habitats..

Floral structure:  Flowers highly reduced, hydophilous, unisexual, and sessile in two rows along a spadix which is subtended by a spathe.  Pollen grains filamentous, up to 2mm long.

Significant features: From the broad perspective of plant evolution, a flowering plant lineage that has returned to the marine home.  Reproductive adaptations are highly specialized.
 

More information on the Zosteraceae and also the Seagrass page.