Starry Stonewort

starry stonewort


  • Forms very dense mats at the water’s surface, interfering with recreational activities.
  • Potentially displaces native plants.
  • Directly impact the habitat used by native fish for spawning.

Description & Origin

  • Starry stonewort is a non-rooted, grass-like algae that can be distinguished by the presence of star-shaped bulbils. This star-shaped structure isn’t available until later summer.
  • Native to Eurasia from the western coast of Europe to Japan, it was first documented along the St. Lawrence River in 1978 and since has spread throughout the Great Lakes region.

Means of spread

The unintentional transfer of plant fragments or bulbils are suspected to be the primary mode of introduction. Be sure to Clean, Drain, Dispose, and Dry!