Curlyleaf Pondweed
Potamogeton crispus
Washington State Classification
Class C — Widespread, County-Selected Control
It is an invasive plant that forms surface mats, interfering with aquatic recreation.
Quick Reference
Identification
Growth Habit
Curly-leaf pondweed grows entirely underwater except for the flower stalk which rises above the water. It has distinctly wavy-edged, crispy olive-green to reddish-brown leaves. It usually grows early in spring and dies back in summer.
Leaves
Leaves alternate, all submersed without leaf stalks. Leaves oblong, stiff, (1.6 to 3.9 inches long by 0.2 to 1 inch wide) with distinctly wavy edges with fine teeth and 3 main veins.
Flowers
Flowers are tiny with 4 petal-like lobes and in spikes around 1 inch long from stalks that are up to 2.8 inches long.
Fruit & Seeds
It is an achene that had 3 ridges and is 0.16 to 0.24 inch (4-6 mm) long, including a 0.08 to 0.12 inch (2-3 mm) beak.
Impact
It is an invasive plant that forms surface mats, interfering with aquatic recreation. Dense colonies can restrict access to docks and sport fishing. Curly-leaf pondweed has been noted as one of the most severe nuisance aquatic plants in the Midwest.
Ecology & Spread
Habitat
It grows in shallow to deep, still or flowing water and is tolerant of disturbance. Please click here to see a county level distribution map of curlyleaf pondweed in Washington.
Spread Mechanisms
Reproduction
It produces seeds, rhizomes and turions, but the importance of seed in the spread of populations is unknown and is assumed to be less important than turions. Typically it reaches peak biomass in the late spring/early summer months and forms turions.
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