Starry Stonewort in Wisconsin
As of September 2026: Starry stonewort is a prohibited invasive species under Wis. Admin. Code NR 40. This page summarizes current DNR guidance; report a suspected find rather than treating it yourself first.
Starry stonewort isn't a plant at all. It's a large algae, and it's one of the newer invasive arrivals on Wisconsin's radar, showing up in a growing number of lakes over the past several years. Because it's still spreading and not yet established statewide, the DNR's first ask is identification and reporting, not do-it-yourself removal.
How to identify it
- Coarse, bushy texture. Branches out in whorls like a native plant such as coontail or chara, which is exactly why it's easy to walk past.
- Star-shaped bulbils. The clearest tell: small white, star-shaped structures (bulbils) at the base of the branches, visible when you pull a strand up and look closely. No native plant in Wisconsin produces this structure.
- Gritty feel and musty smell. Like chara, it can feel gritty from calcium deposits and smells musty or garlic-like when crushed, so texture alone won't separate it from its native lookalike.
Compare it against native chara on the chara and muskgrass identification guide before assuming what you've found.
Why it's treated differently than other invasives
Most established invasives in Wisconsin, like Eurasian watermilfoil, already occupy hundreds of lakes, so hand removal gets a broad exemption because the state can't reasonably require a permit for every homeowner pulling a plant that's already widespread. Starry stonewort is earlier in that timeline. It can form dense mats that outcompete native plants and interfere with boating and fish spawning habitat, and because it's not yet in every watershed, the DNR's priority is stopping new introductions and tracking known populations, not standardizing a removal exemption the way it has for older invasives.
What to do if you find it
If you suspect starry stonewort on your lake, the DNR's guidance is to report it rather than remove it on your own first. Reporting helps confirm identification, since it's genuinely easy to confuse with chara, and it feeds the state's tracking of where the species has spread. Once a population is confirmed, removal generally falls under the same NR 109 (mechanical, manual) or NR 107 (chemical) permit rules that cover any aquatic vegetation, and larger infestations are usually managed through a lake association's aquatic plant management plan rather than one owner's project. See how a lake-wide plan gets approved.
Boat and trailer cleaning matters more with starry stonewort than with most invasives, since its bulbils are small, gritty fragments that can hitch a ride in a live well or on trailer equipment between lakes.
Getting help
Because this species is still spreading and the removal picture is more case-by-case than an established invasive, this is a good one to bring to a professional rather than handling alone. See what to ask a lake weed removal company before hiring anyone to treat a suspected find.