Potamogeton foliosus subsp. fibrillosus
Fibrous pondweed, Fibrous Pondweed
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Family: Potamogetonaceae · Type: Herb · Native
Conservation status: CNPS 2B.3
Potamogeton foliosus subsp. fibrillosus (Fibrous pondweed) is a native California herb in the Potamogetonaceae family, recognized by fibrous stipule remnants distinctive.
Fibrous pondweed is a California native perennial ranked 2B.3 by CNPS, found in northern coastal California, western mountains, and southern eastern Sierra Nevada in shallow water and small streams at elevations below 1,300 meters. Flowering from July to October, this aquatic plant produces small, inconspicuous flowers in interrupted clusters. Growing with slender stems up to 60 centimeters long, it has distinctive nodal glands and delicate underwater growth. Its narrow leaves are 2 to 4 centimeters long and only 1 to 2 millimeters wide, with acute tips and stipules that develop fibrous veins with age. The tiny fruits are pale green, approximately 1.4 to 1.7 millimeters long with a very low keel and minimal beak.
Identification and appearance
Key characters: 13 sympatric species; fibrous stipule remnants distinctive
Habitat and range
Habitat: Shallow water, small streams
Elevation: < 1300 m
Outside California: to Washington, Idaho, Wyoming, Utah
Bloom period
Potamogeton foliosus subsp. fibrillosus blooms Jul-Oct.
Conservation status
CNPS 2B.3
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 foliosus subsp. fibrillosus native to California?
Yes. Potamogeton foliosus subsp. fibrillosus is native to California (recorded as native).
When does Potamogeton foliosus subsp. fibrillosus bloom?
Potamogeton foliosus subsp. fibrillosus blooms Jul-Oct.
What plant family does Potamogeton foliosus subsp. fibrillosus belong to?
Potamogeton foliosus subsp. fibrillosus is in the Potamogetonaceae family, genus Potamogeton.
Is Potamogeton foliosus subsp. fibrillosus rare or endangered?
Potamogeton foliosus subsp. fibrillosus carries California Rare Plant Rank 2B.3, state rank S1S2.
What habitat does Potamogeton foliosus subsp. fibrillosus grow in?
Potamogeton foliosus subsp. fibrillosus grows in Shallow water, small streams.
Related species
Other California species in the same genus, family, or bioregion.
Sources: Jepson eFlora · CalPhotos · CDFW CNDDB
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.