Large alga
Starry Stonewort
Nitellopsis obtusa
These illustrations are AI-generated, not photographs, and are not to scale. They show what to look for; they are not a substitute for an expert identification.
How to identify it
Size: Strands can be several feet long. The star-shaped bulbils are only a few millimeters across.
- Not a true plant but a large green alga with a stem-like body.
- Rings (whorls) of long, smooth, bright-green branchlets of different lengths.
- Long gaps between the rings.
- Tiny pale, star-shaped bulbils on the root-like strands near the base. These are the giveaway: gently pull up a clump to look.
Don’t confuse it with
Native Chara, also called muskgrass, feels rough or gritty and often smells musky. Native Nitella has branchlets that fork evenly at the tips and no star-shaped bulbils.
Where it came from
Native to Europe and western Asia.
First found in North America in the St. Lawrence River in the late 1970s, likely carried in ships' ballast water. Pieces and bulbils reach inland lakes on boats, trailers and gear.
Earliest dated Michigan record: 1983, Belle Isle, Detroit. This is the oldest dated record in the USGS non-native species database, not necessarily when it first arrived.
Why it matters
It can grow into thick mats several feet deep that crowd out native plants, cover the areas where fish spawn and make boating and swimming difficult.
Michigan law
Prohibited under Part 413 of Michigan's Natural Resources and Environmental Protection Act. It is illegal to possess, introduce, import, sell or offer to sell it as a live organism, except in the limited cases the law allows. The state uses “prohibited” for species that are not yet widespread in Michigan. The state’s page on this species.
If you find it
- Don’t move it. Michigan law requires boaters to remove all aquatic plants from boats, equipment and trailers before launching. Before trailering, you must pull all drain plugs, drain live wells and bilges, and make sure the boat and trailer are free of aquatic plants and animals. What the law requires
- Never release bait. Releasing baitfish into Michigan waters is illegal. Put unused bait in the trash, never in the water.
- Report it. Take a photo, note where you saw it, and report it to the Midwest Invasive Species Information Network (MISIN) or through Michigan’s invasive species program. Experts there can confirm what you found.
- Ask before removing or treating. Treating a lake with herbicides or other chemicals needs a state permit, and some removal work does too. Start with the state’s Aquatic Nuisance Control program before taking action.
Michigan lakes where it has been recorded
101 Michigan lakes on this site have a record of this species.
Alcona
Allegan
Alpena
Calhoun
Clinton
Crawford
Genesee
Hillsdale
Ingham
Ionia
Jackson
Center Lake, Crispell Lake, Farewell Lake, Grass Lake, Pleasant Lake, Round Lake, Vineyard Lake, Wamplers Lake
Kalamazoo
Lapeer
Lenawee
Livingston
Hi-Land Lake, Lake Chemung, Tamarack Lake, Thompson Lake, Whitewood Lakes, Whitmore Lake, Woodland Lake, Zukey Lake
Mackinac
Macomb
Mason
Mecosta
Montcalm
Muskegon
Newaygo
Oakland
Bass Lake, Big Lake, Cass Lake, Cedar Island Lake, Duck Lake, Huntoon Lake, Kent Lake, Lake Louise, Lake Oakland, Lake Orion, Lakeville Lake, Loon Lake, Lower Straits Lake, Maceday Lake, Orchard Lake, Pontiac Lake, Proud Lake, Round Lake, Scott Lake, Tipsico Lake, Upper Straits Lake, Walled Lake, Walters Lake, White Lake, Williams Lake, Wolverine Lake
Roscommon
Van Buren
Washtenaw
A lake that is not listed may still have it. Records exist only where someone found the species and reported it, so “not recorded” does not mean “not present.”
Lake records: Midwest Glacial Lakes Partnership Conservation Planner; underlying records from the USGS Nonindigenous Aquatic Species database.
Sources
- Michigan Invasive Species Program: Starry stonewort
- Michigan Clean Water Corps: Starry stonewort fact sheet
- Michigan Compiled Laws, section 324.41302 (prohibited and restricted species)
Earliest dated record: USGS Nonindigenous Aquatic Species database.