Ludwigia peploides ssp. montevidensis and L. hexapetala (water primrose)

• ODA “B” rank species (ODA ranking page)

Several species and subspecies of water primrose, a plant native to South America, have been a substantial problem in the drainage and irrigation canals of central California. In recent years, these species have also become a concern in the mid and lower Willamette, as well as in the Puget Sound region. In the Portland area, most patches of Ludwigia are known along the slower-moving waters of the Columbia Slough.