Potamogeton crispus is a perennial, submerged, aquatic herb that is native to Eurasia.
Foliage
Leaves are sessile, oblong, stiff, 1.6-3.9 in. (4-10 cm) long, 0.2-0.4 in. (5-10 mm) wide, translucent and have noticeably curly margins (resemble lasagna noodles).
Flowers
Flowering occurs in the summer to early fall, when emergent flowers develop. Flowers are brown, inconspicuous and wind pollinated.
Fruit
Fruits are flat with a pointed beak and are 0.16-0.24 in. (4-6 mm) long. The seed do not seem to be viable. In the midsummer plants form turions (vegetative buds), from which new growth starts in fall or winter.
Ecological Threat
Potamogeton crispus tolerates fresh or slightly brackish water and can grow in shallow, deep, still or flowing water. Plants can grow in clear or turbid water, but are mostly shade intolerant. The method of introduction is unclear and it may have been introduced as a hitchhiker on boats, through the aquarium trade, or accidently when stock from a fish hatchery was released. It was first collected in 1860.