Hydrocharitaceae

Defining Characteristics

• Obligately aquatic herbs — freshwater and marine (includes seagrasses)
• Flowers typically with 3 petals and 3 sepals (trimerous), unisexual in many genera
• Often elaborate pollination mechanisms — floating pollen on the water surface or underwater pollination
• Leaves highly variable: ribbon-like, whorled -linear, floating rosettes , or reduced
• Fruit a berry or capsule , ripening underwater
• Vegetative reproduction often dominant — stolons, turions, fragmentation

Notable Genera

• Vallisneria (tape-grass, eelgrass)
• Elodea (waterweeds)
• Najas (water-nymphs, guppy grass)
• Hydrilla (hydrilla — invasive)
• Egeria (Brazilian waterweed)
• Blyxa (blyxa)

Notes

A cornerstone family for the aquarium hobby — Vallisneria, Elodea, Egeria, Najas, and Blyxa are among the most commonly traded aquatic plants. Also ecologically critical as submerged aquatic vegetation (SAV) providing habitat and oxygenation in freshwater systems. Hydrilla verticillata is one of the world's worst aquatic invasive species. The genus Thalassia (turtle grass) forms vast seagrass meadows in tropical marine environments. Pollination strategies in this family range from conventional insect pollination to surface-floating pollen rafts.