Primrose-willow has five-petaled yellow flowers that are produced on stalks. Image source: https://kingcounty.gov/en/legacy/services/environment/animals-and-plants/noxious-weeds/weed-identification/floating-primrose-willow.
SCIENTIFIC NAME:Ludwigia peploides
ORIGIN:Central and South America, also parts of the southern United States
DESCRIPTION:Primrose-willow is an aquatic perennial species that floats on water or sprawls along mud in wet environments. It has alternate leaves with smooth margins that can grow up to 3.5 inches long, and leaf shape varies from lance to egg shaped. Primrose-willow stems are light green to red in color and float along the water surface or grow prostrate in mud. Showy, yellow five-petaled flowers are produced on stalks attached to the leaf axils from late spring to early fall. Later in the season, cylindrical seed capsules are formed.
HABITAT:Primrose-willow grows in water or wet areas and prefers full sun with wet conditions or muddy soil. It grows in shallow freshwater habitats, up to 10 feet deep, including borders of ponds, shallow sections of lakes, slow-moving streams, swamps and marshes.
THREAT:Primrose-willow creates dense mats of vegetation that can cover the surface of water or mud. These dense mats may reduce water flow, impact irrigation and drainage, displace native species and limit water use for recreational and industrial purposes. Primrose-willow is allelopathic and can inhibit the growth of native species.
Manual and mechanical control of primrose-willow is not recommended as disturbance of this species may cause fragmentation and help spread the plant. If manual removal is used on small, new patches, be sure to remove the entire plant, contain all root and stem fragments, and dispose of all plant material in landfill-bound trash. Chemical control is possible but can be challenging in aquatic habitats. Prevention is the most effective control.
WNY PRISM PRIORITY:
Approaching Region Priority Species
Tier 1 - Raise Awareness
NYS Prohibited and Regulated Species - Part 575:
Primrose-willow is a prohibited species in New York State – for more information on Prohibited and Regulated Species, visit http://www.dec.ny.gov/animals/99141.html.
PATHWAYS OF INVASION:
Primrose-willow spreads by fragmentation of stems and roots which are spread by water, animals and on boats and fishing gear.
MAP (via iMapInvasives):
To view more information for each point, zoom in, click on the point and select the "Maximize" symbol. Click "More info" to open the iMapInvasives record.
This map shows confirmed observations (green points) submitted to the NYS Invasive Species Database.
Absence of data does not necessarily mean absence of the species at that site, but that it has not been reported there.
For more information, please visit iMapInvasives.