starry stonewort
(Nitellopsis obtusa)
This species is Introduced in the United States
Origin
Native to Eurasia.
Appearance
Nitellopsis obtusa is a macroalgae that resembles true plants and invades all manner of fresh or brackish water, including lakes, ponds, and slow-moving rivers. It forms dense mats which resemble underwater hills or mounds. In North America, only male individuals have been recorded, which have no roots and are therefore easy to spread to new areas.
Foliage
Made up of thin, light green stems and branchlets similar in appearance to thick fishing line. Branchlets come in whorls of 4-6 and have blunt tips.
Flowers
Does not flower.
Fruit
White, star-shaped bulbils, which give the species its name, are produced at the nodes, generally 3-6 mm wide. Bulbils are deposited in the mud, allowing the species to be easily spread.
Ecological threat
Reduces biodiversity by forming dense mats and competes aggressively with native plants. These mats can impede movement of fish, spawning activity, water flow, and recreational activities, such as swimming, boating, and fishing. Once introduced to a new area, Nitellopsis obtusa can establish and spread very quickly. The species is spread primarily by boating, but it is suspected that species like waterfowl can transport fragments to other unconnected water bodies as well.
Citations
Kipp, R.M., M. McCarthy, A. Fusaro, and I.A. Pfingsten. 2021. Nitellopsis obtusa (Desvaux in Loiseleur) J. Groves, 1919. U.S. Geological Survey, Nonindigenous Aquatic Species Database, Gainesville, FL, Retrieved from https://nas.er.usgs.gov/queries/FactSheet.aspx?SpeciesID=1688
Ontario Federation of Anglers and Hunters. Starry Stonewort. Invading Species Awareness Program, retrieved April 14, 2021, http://www.invadingspecies.com/starry-stonewort/
Ontario Federation of Anglers and Hunters. 2021. The Lake Simcoe Aquatic Invasive Species Guide. Retrieved from www.invadingspecies.com.
Native to Eurasia.
Appearance
Nitellopsis obtusa is a macroalgae that resembles true plants and invades all manner of fresh or brackish water, including lakes, ponds, and slow-moving rivers. It forms dense mats which resemble underwater hills or mounds. In North America, only male individuals have been recorded, which have no roots and are therefore easy to spread to new areas.
Foliage
Made up of thin, light green stems and branchlets similar in appearance to thick fishing line. Branchlets come in whorls of 4-6 and have blunt tips.
Flowers
Does not flower.
Fruit
White, star-shaped bulbils, which give the species its name, are produced at the nodes, generally 3-6 mm wide. Bulbils are deposited in the mud, allowing the species to be easily spread.
Ecological threat
Reduces biodiversity by forming dense mats and competes aggressively with native plants. These mats can impede movement of fish, spawning activity, water flow, and recreational activities, such as swimming, boating, and fishing. Once introduced to a new area, Nitellopsis obtusa can establish and spread very quickly. The species is spread primarily by boating, but it is suspected that species like waterfowl can transport fragments to other unconnected water bodies as well.
Citations
Kipp, R.M., M. McCarthy, A. Fusaro, and I.A. Pfingsten. 2021. Nitellopsis obtusa (Desvaux in Loiseleur) J. Groves, 1919. U.S. Geological Survey, Nonindigenous Aquatic Species Database, Gainesville, FL, Retrieved from https://nas.er.usgs.gov/queries/FactSheet.aspx?SpeciesID=1688
Ontario Federation of Anglers and Hunters. Starry Stonewort. Invading Species Awareness Program, retrieved April 14, 2021, http://www.invadingspecies.com/starry-stonewort/
Ontario Federation of Anglers and Hunters. 2021. The Lake Simcoe Aquatic Invasive Species Guide. Retrieved from www.invadingspecies.com.
Selected Images
Maps
EDDMapS Distribution - This map is incomplete and is based only on current site and county level reports made by experts, herbaria, and literature. For more information, visit www.eddmaps.org
State Lists - This map identifies those states that have this species on their invasive species list or law.
Invasive Listing Sources
- Indiana Invasive Species Council - Invasive Plant List
- Michigan’s Prohibited and Restricted Species
- Minnesota DNR invasive species list
- New Jersey Invasive Species Strike Team 2017 Invasive Species List
- Ontario’s Invading Species Awareness Program Tracked Species List
- Pennsylvania Department of Conservation and Natural Resources Invasive Plants
- Pennsylvania Noxious Weeds
- Pennsylvania's Field Guide to Aquatic Invasive Species
- Wisconsin's Invasive species rule – NR 40
Taxonomic Rank
| Domain: Eukarya |
| Kingdom: Plantae |
| Phylum: Charophyta |
| Class: Charophyceae |
| Order: Charales |
| Family: Feistiellaceae |
| Genus: Nitellopsis |
| Nitellopsis obtusa |