Brittle waternymph

Scientific Name: Najas minor

Robert H. Mohlenbrock @ USDA-NRCS PLANTS Database / USDA NRCS. 1995. Northeast wetland flora: Field office guide to plant species. Northeast National Technical Center, Chester, PA.Copyright Info

Identification: Brittle waternymph is an annual aquatic submersed plant. It is a slender, branching plant with paired leaves that are sometimes bunched or arranged in a ring around the stem. The narrow leaves are typically stiff, curled, and pointed, and are about 0.04 inch (1 mm) wide and 0.2 to 1.4 inches (0.5-3.5 cm) long. Large, visible spines along its leaves are a distinguishing feature of this species. Brittle waternymph is also known as brittle naiad, brittle-leaf naiad, minor naiad, and European naiad.

Size: Although its growth is usually compact and relatively bushy, the highly branched stems of brittle waternymph can grow up to 4 feet (1.2 m) in length and can fragment easily.

Native Range: Brittle waternymph is native to Europe and western Asia.

Table 1. Great Lakes region nonindigenous occurrences, the earliest and latest observations in each state/province, and the tally and names of HUCs with observations†. Names and dates are hyperlinked to their relevant specimen records. The list of references for all nonindigenous occurrences of Najas minor are found here.

Full list of USGS occurrences

State/ProvinceYear of earliest observationYear of last observationTotal HUCs with observations†HUCs with observations†
Illinois200120011Little Calumet-Galien
Michigan194920135Clinton; Huron; Kalamazoo; Lake Huron; Ottawa-Stony
New York1935201814Chautauqua-Conneaut; Grass; Great Lakes Region; Irondequoit-Ninemile; Lake Champlain; Lake Ontario; Lower Genesee; Mettawee River; Oak Orchard-Twelvemile; Oneida; Oswego; Salmon-Sandy; Seneca; Upper Genesee
Ohio1932201811Black-Rocky; Cedar-Portage; Cuyahoga; Grand; Huron-Vermilion; Lake Erie; Lower Maumee; Sandusky; Southern Lake Erie; Tiffin; Western Lake Erie
Pennsylvania198720021Lake Erie
Vermont196019651Lake Champlain
Wisconsin200920142Upper Fox; Wolf

Table last updated 10/18/2019

† Populations may not be currently present.

* HUCs are not listed for areas where the observation(s) cannot be approximated to a HUC (e.g. state centroids or Canadian provinces).

Means of Introduction: It is not clear how this species was introduced to North America. It does not appear to be widely used as an aquarium or fish pond plant, but it could have been accidentally introduced with more commonly cultivated species. Alternatively, it could have been introduced to the Great Lakes, the Hudson River, or the upper Chesapeake Bay via commercial shipping. It is easily spread through its many small seeds and plant fragments that attach to boats, trailers, or waterfowl.

Status: This species was first documented in North America in the 1930s in Ohio, New York, and the Chesapeake Bay. In 1939, it was first reported in the Great Lakes in Lake Ontario. It is established from Ontario west to Illinois and south to Florida. This plant has spread rapidly in the southeast and mid-Atlantic states, and has been reported as far west as Oklahoma.

Author: Illinois-Indiana Sea Grant

Contributing Agencies:
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Revision Date: 9/25/2012

Citation for this information:
Illinois-Indiana Sea Grant, 2019, Brittle waternymph: U.S. Geological Survey, Nonindigenous Aquatic Species Database, Gainesville, FL, and NOAA Great Lakes Aquatic Nonindigenous Species Information System, Ann Arbor, MI,, Revision Date: 9/25/2012, Access Date: 11/18/2019

This information is preliminary or provisional and is subject to revision. It is being provided to meet the need for timely best science. The information has not received final approval by the U.S. Geological Survey (USGS) and is provided on the condition that neither the USGS nor the U.S. Government shall be held liable for any damages resulting from the authorized or unauthorized use of the information.