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Starry Stonewort

starry stonewort, Nitellopsis obtusa, photo by Paul Skawinski

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Common Name: Starry stonewort
Scientific Name: Nitellopsis obtusa
Origin: Eurasia


Starry stonewort looks like a rooted plant, but is actually an algae related to the native Chara. It can form dense mats on the lake bottom, and has long, uneven-length, gelatinous branches that look angular at each joint. It may also have one cream colored bulb at the base of each branch cluster.


Starry stonewort is sometimes found in deep, slow moving water where other plants are scarce, typically near docks and marinas. It is known to maintain permanent populations in freshwater or brackish water with salinity of up to 5%. It can tolerate salinity fluctuations up to 17% for around 1 week. Under high salt loading or unfavorable environmental conditions, it has the ability to shift cells from a high-energy state to a state of passive permeability.


By forming dense mats of vegetation, starry stonewort can reduce the diversity of aquatic plants in a lake. It can also impede movement of fish and other animals, and may impact spawning activity of some fishes. Mats growing to the surface can reduce water flow and make recreational activities difficult.


Manual removal of starry stonewort is possible, but difficult, and may be impractical on a large scale. Abundant bulbils on the rhizoids can dislodge if disturbed, and will sprout new individuals. Manual removal efforts must emphasize careful removal of these bulbils. Some chemical herbicides and algaecides have been effective at reducing starry stonewort. Herbicide applications may be less effective on tall stands of starry stonewort, as the chemical is quickly absorbed into the upper parts of the algae, leaving the lower parts unharmed. An effective biological control agent is not known at this time.

Regional Distribution

Locally Common

WNY PRISM Priority

Tier 3 – Containment

Invasive Species Priorities – Tier Chart


Starry stonewort was  introduced to the Great Lakes through ship ballast water. It is spreads through star shaped bubils and plant fragments on watercraft.


Starry stonewort is a prohibited species in New York State – for more information on Prohibited and Regulated Species, visit