Potamogeton gramineus
Grass-leaved pondweed
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Family: Potamogetonaceae · Type: Herb · Native
Potamogeton gramineus (Grass-leaved pondweed) is a native California herb in the Potamogetonaceae family, recognized by broad elliptic submersed leaves plus floating leaves on short branches distinctive.
Grass-leaved pondweed is a native perennial aquatic plant found in the Klamath Ranges, northern California coast ranges, high Cascade Range, Sierra Nevada, San Francisco Bay Area, and Great Basin in shallow water, ponds, lakes, and bogs at elevations of 900 to 2,750 meters. Flowering from July to August, this plant produces small underwater flowers on compact inflorescences 1 to 4 centimeters long. Growing with branching stems up to 100 centimeters long and matted rhizomes, it forms intricate underwater colonies with distinctive leaf types. Its underwater leaves are elliptic, 2 to 10 centimeters long and 10 to 27 millimeters wide, with 3 to 9 delicate veins, while floating leaves are shorter and broader with 11 to 13 veins. The fruit is small, approximately 2 millimeters long with three distinctive keels and a short erect beak.
Identification and appearance
Key characters: 16 sympatric species; broad elliptic submersed leaves plus floating leaves on short branches distinctive
Habitat and range
Habitat: Uncommon. Shallow water, ponds, lakes, bogs
Elevation: 900-2750 m
Outside California: to Alaska, Greenland, Arizona, Eurasia
Bloom period
Potamogeton gramineus blooms Jul-Aug.
How to tell it apart
vs Persicaria: Potamogeton flowers float on water; Persicaria has terrestrial pink/white flower spikes above solid ground.; vs Stuckenia: Potamogeton flowers emerge above water on stiff stalks; Stuckenia flowers stay underwater on flexible stalks.; vs Alisma: Potamogeton has inconspicuous spike flowers; Alisma has showy white three-petaled flowers in branched clusters.; vs Ranunculus: Potamogeton has tiny greenish spike flowers; Ranunculus has bright yellow buttercup flowers with visible petals.; vs Myriophyllum: Potamogeton has broad or ribbon-like leaves; Myriophyllum has feathery, finely divided leaves like a bottlebrush.
Frequently asked questions
Is Potamogeton gramineus native to California?
Yes. Potamogeton gramineus is native to California (recorded as native).
When does Potamogeton gramineus bloom?
Potamogeton gramineus blooms Jul-Aug.
What plant family does Potamogeton gramineus belong to?
Potamogeton gramineus is in the Potamogetonaceae family, genus Potamogeton.
What habitat does Potamogeton gramineus grow in?
Potamogeton gramineus grows in Uncommon. Shallow water, ponds, lakes, bogs.
Related species
Other California species in the same genus, family, or bioregion.
Sources: Jepson eFlora · Index of California Plant Names · CalPhotos
Last updated 2026-10-07
Data from The California Species Project — 14,000+ California species with verified data from CNPS, CDFW, USFWS, Cal-IPC, and more.