European/Common frog-bit

Hydrocharis morsus-ranae


European frogbit. Credit: H. Zwitzer.
  • Free-floating herbaceous annual aquatic plant
  • Leathery, heart-shaped leaves on long stems
  • Small white flowers have three petals
  • Flowers have an outer whorl of three greenish-red sepals
  • Prefers calm, open, calcium-rich waters; grows in wetlands, ditches, along protected edges of lakes & rivers
  • Reproduces by stolons & turions (‘winter buds’)
  • Native to Europe and northern Asia

Consequences of invasion

  • Extremely rapid growth during the summer months results in the formation of large masses of densely tangled floating mats of interlocking vegetation!
  • These plant masses impede water-recreation activities, crowd out native aquatic vegetation, and restrict dissolved gases & nutrients, which can impact fish
  • Can dominate wetlands & reduce valuable habitat for native plant and animals

Introduction and spread

  • This plant has a great capacity for vegetative (stolons & turions) reproduction, allowing it to spread and proliferate quickly.
  • Originally introduced to North America through the horticultural industry
  • European frogbit is now commonly spread by watercraft and connected waterways.

Integrated pest management options

  • Prevention: Since “hitchhiking” on watercraft is one of the primary means by which this plant spreads, following the Clean, Drain, Dry method can help protect our waters
  • Prevention: Be PlantWise! Choose non-invasive or native plants for your water gardens and ponds

Additional resources