Starry stonewort

Scientific Name: Nitellopsis obtusa

U.S. Geological Survey Great Lakes Science CenterCopyright Info

Identification: Starry stonewort is a green alga with long, relatively straight branches of uneven length. Branches are arranged in a circle around the main stem. There may be a creamy white bulb at the base of each of these circular clusters of branches.

Size: The main stem can reach 32 inches (80 cm) in length. Branches and stems are very thin.

Native Range: Starry stonewort is native to Eurasia, from the west coast of Europe to Japan.

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 Nitellopsis obtusa are found here.

Full list of USGS occurrences

State/ProvinceYear of earliest observationYear of last observationTotal HUCs with observations†HUCs with observations†
Indiana200820161St. Joseph
Michigan1983201827Au Gres-Rifle; Au Sable; Black-Macatawa; Brevoort-Millecoquins; Clinton; Detroit; Flint; Huron; Kalamazoo; Lake Erie; Lake Huron; Lake St. Clair; Little Calumet-Galien; Lone Lake-Ocqueoc; Lower Grand; Maple; Muskegon; Pere Marquette-White; Pigeon-Wiscoggin; Raisin; Shiawassee; St. Clair; St. Joseph; Thornapple; Tiffin; Tittabawassee; Upper Grand
New York1978201710Headwaters St. Lawrence River; Indian; Irondequoit-Ninemile; Lake Ontario; Oak Orchard-Twelvemile; Oneida; Oswegatchie; Raisin River-St. Lawrence River; Salmon-Sandy; Seneca
Ohio201720171Lake Erie
Pennsylvania200920151Lake Erie
Vermont201520161St. Francois River
Wisconsin201520183Door-Kewaunee; Lake Michigan; Milwaukee

Table last updated 9/30/2019

† 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: This species was probably introduced to the Great Lakes by water discharged from transoceanic ships.

Status: In the Great Lakes basin, starry stonewort was first discovered in 1978 in the St. Lawrence River. In 1983, it was found in the St. Clair and Detroit rivers.

Other Resources:
GLANSIS Technical Species Profile

Starry Stonewort (MI Lake Info)

Author: Illinois-Indiana Sea Grant

Contributing Agencies:
NOAA Sea Grant GLRI Logo

Revision Date: 4/24/2012

Citation for this information:
Illinois-Indiana Sea Grant, 2019, Starry stonewort: U.S. Geological Survey, Nonindigenous Aquatic Species Database, Gainesville, FL, and NOAA Great Lakes Aquatic Nonindigenous Species Information System, Ann Arbor, MI,, Revision Date: 4/24/2012, Access Date: 10/17/2019

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.