Brittle Naiad (aka Brittle Waternymph)
Photo: Don Cameron, Maine Natural Areas Program. Drawing: USDA NRSC.
Brittle naiad, also known as brittle waternymph, grows tufts of spiny, stiff, arched leaves on stems that may be up to 2.5 meters long. Unlike native naiads, the serrations on brittle naiad leaves are visible without magnification. Spindle-shaped seeds grow in leaf axils; flowers are inconspicuous.
Brittle naiad was introduced to the United States from Europe in the early 1900s. It is a true annual, reproducing primarily by seed. Relatively small infestations may produce tens of millions of seeds that are dispersed on air and water currents. It has been confirmed in Maine, New Hampshire, Vermont and Massachusetts.