Other Common Names: slender arrowhead, Chinese arrowhead
Weed class: B
Year Listed: 2005
Native to: Eastern and Central North America and Cuba
Is this Weed Toxic?:
not known to be
This plant is also on the Washington State quarantine list. It is prohibited to transport, buy, sell, offer for sale, or distribute plants or plant parts of quarantined species into or within the state of Washington or to sell, offer for sale, or distribute seed packets of seed, flower seed blends, or wildflower mixes of quarantined species into or within the state of Washington. Please see WAC 16-752 for more information on the quarantine list. For questions about the quarantine list, contact the Washington State Department of Agriculture's Plant Services Program at (360) 902-1874 or email PlantServices@agr.wa.gov.
Why Is It a Noxious Weed?
Although grass-leaved arrowhead is native to the eastern region of North America, it was introduced elsewhere mainly as an aquatic ornamental. Where introduced outside of its native range, it has become a serious pest plant.
How would I identify it?
Grass-leaved arrowhead is an emergent or submersed, perennial, aquatic flowering plant. It has both emergent and underwater leaves.
Flowers are white and sometimes pink and around 1 inch in diameter. They occur in 2 to 12 groups of 3 flowered whorls and are found at the end of the flower stem.
Leaves are basal. Emergent leaves are linear to oval tapering abruptly to a point with a triangular petiole. They are 0.4 to 9.8 inches long and 0.8 to 3.1 inches wide. Submerged leaves are strap-shaped, up to 20 inches long and 1 inch wide.
Flowering stems up to about 3.25 feet tall.
Fruit Seed Description
Seeds are achenes, small with a lateral beak.
Where does it grow?
It grows best in shallow water up to 6.6 feet deep in static or slow moving freshwater such as lakes, streams and pond margins. Please click here to see a county level distribution map of grass-leaved arrowhead in Washington.
How Does it Reproduce?
Grass-leaved arrowhead reproduces mainly by rhizomes; it can also reproduce by seed.
How Do I Control It?
Use of pesticides in water is regulated in Washington State. All applicators must have an aquatic endorsement on their pesticide applicators license, which is issued by the Washington Department of Agriculture. In addition, coverage under a permit issued by the Department of Ecology is required. See http://www.ecy.wa.gov/programs/wq/pesticides/index.html for details or contact your county noxious weed coordinator.
For More Information
See our Written Findings for more information about grass leaved arrowhead (Sagittaria graminea).