Grass-Leaved Arrowhead
Sagittaria graminea
Washington State Classification
Class B — Control Required (Designated)
Although grass-leaved arrowhead is native to the eastern region of North America, it was introduced elsewhere mainly as an aquatic ornamental.
Required control in Region 1 (all western Washington counties)
Quick Reference
Identification
Growth Habit
Grass-leaved arrowhead is an emergent or submersed, perennial, aquatic flowering plant. It has both emergent and underwater leaves.
Leaves
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.
Flowers
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.
Fruit & Seeds
Seeds are achenes, small with a lateral beak.
Impact
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.
Ecology & Spread
Habitat
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.
Spread Mechanisms
Reproduction
Grass leaved arrowhead reproduces mainly by rhizomes; it can also reproduce by seed.
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