Creeping Water Primrose
Creeping Water Primrose has infested many waterways from North Carolina southwards. This plant typically begins infesting aquatic sites by establishing right along the shoreline. Over time the rhizomes "creep" out to deeper water. It forms dense patches that are often monotypic. Sometimes found mixed with Alligatorweed or Parrotfeather (both are also invasive).
Ovate leaves arranged as rosettes develop in the winter/spring and float at the surface. As summer arrives the new leaves are lanceolate (oblong with pointed tips). The alternate pattern of the leaves becomes more apparent once the plants develop past the rosette stage. Yellow flowers with 5 to 6 petals are born well above the surface. Blooms throughout the summer. Stems turn from light green to reddish brown and begin to lose their leaves towards the end of summer and into fall.
There are multiple species of Water Primrose and some require carful observation to distinguish.
Fact Sheet: Creeping Water Primrose
Photos from NC Piedmont and Coastal Plain.
Credit: Rob Emens (NCDEQ - Div. of Water Resouces)