Description:
Water primrose is an aquatic perennial herb. The stems are glabrous to sparsely pubescent, and they sprawl, or grow horizontally on water or mud. The leaves are alternate. Early growth consists of rosette-like clusters of rounded (suborbicular to spatulate) leaves on the water surface. At flowering the leaves lengthen to a willow-like shape (lanceolate or elliptic). The stems also lengthen at flowering, and grow upright. Flowering stems can rise to 3 feet above the water surface.

• Mechanical: Cutting or covering with opaque materials may be effective (DOE Bulletin).
• Biological: Grass carp would not find water primrose palatable (DOE Bulletin).
• Herbicide: Rodeo may be effective (DOE Bulletin). Refer to the State Noxious Weed Control Board site

For More Information:
Detailed information about Water Primrose is available at the Washington State Noxious Weed Control Board Web Site.