Invasive species fact sheets

Invasive aquatic plants

Brittle Naiad (Najas minor), also called Brittle Waternymph


Brittle Naiad
Brittle Naiad - photo from MNDNR

Appearance: Submersed aquatic plant.

Leaves: Leaves are opposite (leaves are in pairs along the stem), but leaves sometimes appear to be in a whorl at tip. Leaves are 1 to 2 inches long, toothed, stiff, and pointed.

Flowers: Small and inconspicuous. Found in leaf axils.

Reproduction: Brittle naiad is an annual plant that spreads by seeds and plant fragments. The plant is very brittle so it easily breaks into pieces which can spread the plant to new locations. Seeds mature in summer and late fall. Seeds germinate in the spring.

Note on identification: Brittle naiad can be easily confused with native pondweeds and naiads. Brittle naiad differs from coontail in that brittle naiad leaves are in pairs of two while coontail leaves are in whorls of 4 or 5. See the reporting invasive aquatic plants webpage if you are unsure of identification or wish to report a new location of brittle naiad.

Ecological Threat:

  • Brittle naiad is native to Europe and Asia and has been introduced to the United States. Brittle naiad can form dense mats that out compete native species and can interfere with recreational activities such as boating, swimming, and fishing.
  • Brittle naiad is a prohibited invasive species in Minnesota

Control Methods:

Prevention: Brittle naiad is reported in very few lakes in Minnesota (see infested waters list). By cleaning all plant parts off of boats and water-related equipment, we can prevent the spread of brittle naiad to additional lakes.

Mechanical or chemical: See DNR regulations for submersed aquatic plant management strategies and regulations. 

Additional resources: