Water primrose is a perennial plant that stands erect along the shoreline but also forms long runners (up to 16 feet) that creep across wet soil or float out across the water surface. These runners form roots at their nodes. Leaves range from lance-shaped or willow-like (2 to inches long by 1/2 to 1 inch wide) on the erect stems to round or oval 91 to 2 inches in diameter on the floating stems. Leaves can be green to reddish depending on the species. The single flowers are yellow with 4 or 5 petals depending on the species. Flowers vary in size from 1 inch to 2 inches in diameter. Submerged portions of all aquatic plants provide habitats for many micro and macro invertebrates. These invertebrates in turn are used as food by fish and other wildlife species (e.g. amphibians, reptiles, ducks, etc). After aquatic plants die, their decomposition by bacteria and fungi provides food (called "detritus") for many aquatic invertebrates. Ducks and other waterfowl will consume the seeds of water primrose.

Herbicide Management Options:

Habitat: contains the active ingredient, imazapyr, which inhibits the plant enzyme AHAS (acetohydroxyaced synthase). Habitat is a systemic herbicide that is effective on post-emergent floating and emergent aquatic vegetation. Imazapyr is effective at low-volume rates and does not contain heavy metals, organochlorides or phosphates, making it safe to humans and livestock. Habitat requires the use of a non-ionic sufactant when applying on post-emergent vegetation.
 

Rodeo: is a liquid glyphosate formulation and has been effective on Water Primrose. This is a broad spectrum, systemic herbicide. Systemic herbicides are absorbed and move within the plant to the site of action. Systemic herbicides tend to act more slowly than contact herbicides. An aquatically registered surfactant (see the label) will have to be added to the Rodeo solution for good results.

Clipper:
 

Biological Management Options: There are no known Biological Management Options.