Appearance
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 does 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 accidentally when stock from a fish hatchery was released. It was first collected in 1860.

Resources

• Global Invasive Species Database - Invasive Species Specialist Group

Selected Images

Maps

Invasive Listing Sources

• Alabama Noxious Weeds - Class C Noxious Weed
• Alberta Fisheries Act
• Apalachicola Invasive Working Group
• California Invasive Plant Council
• Connecticut Invasive Plant List
• Connecticut Invasive Plant Working Group
• Georgia Exotic Pest Plant Council - Category 3
• Hoffman, R. & K. Kearns, Eds. 1997. Wisconsin manual of control recommendations for ecologically invasive plants. Wisconsin Dept. Natural Resources, Bureau of Endangered Resources. Madison, Wisconsin. 102pp.
• Idaho Noxious Weeds
• Indiana Invasive Species Council - Invasive Plant List
• Indiana Pest Species
• Indiana Prohibited Plant Species
• Invasive Plant Association of Wisconsin
• Invasive Plant Species of West Virginia
• Jil M. Swearingen, Survey of invasive plants occurring on National Park Service lands, 2000-2007
• Kentucky Exotic Pest Plant Council - Significant Threat
• Maryland Department of Natural Resources Policy: Restriction on Planting Exotic Invasive Plants
• Maryland Invasive Species Council - Invasive Species of Concern in Maryland
• Massachusetts Invasive Plants Advisory Group List
• Massachusetts Noxious Weeds
• Massachusetts Prohibited Plant List
• Michigan’s Prohibited and Restricted Species
• Mid-Atlantic Field Guide to Aquatic Invasive Species
• Minnesota DNR invasive species list
• Montana Noxious Weeds
• National Park Service, Mid-Atlantic Exotic Plant Management Team Invasive Plant List
• Nevada EDRR
• Nevada Noxious Weeds
• New Hampshire Invasive Species Committee. 2005. Guide to Invasive Upland Plant Species in New Hampshire. New Hampshire Department of Agriculture,  Markets and Food Plant Industry Division and New Hampshire Invasive Species Committee.
• New Hampshire Prohibited Aquatic Species
• New Jersey Invasive Species Strike Team 2017 Invasive Species List
• New Mexico Noxious Weeds
• New York Regulated and Prohibited Invasive Species - Prohibited
• Nonnative Invasive Species in Southern Forest and Grassland Ecosystems
• Ohio Invasive Species Council
• Ontario’s Invading Species Awareness Program Tracked Species List
• Pacific Northwest Exotic Pest Plant Council, 1998
• Pennsylvania Department of Conservation and Natural Resources Invasive Plants
• Pennsylvania's Field Guide to Aquatic Invasive Species
• Rhode Island Natural History Survey
• South Carolina Invasive Pest Council
• Vermont Noxious Weeds
• Virginia Invasive Plant Species List
• Washington Noxious Weeds
• WeedUS - Database of Plants Invading Natural Areas in the United States
• West Virginia Invasive Species Strategic Plan and Volunteer Guidelines 2014
• West Virginia Native Plant Society, Flora West Virginia Project, and West Virginia Curatorial Database System, September 3, 1999
• Wisconsin Noxious Weeds
• Wisconsin's Invasive species rule – NR 40

References