Potamogeton robbinsii
Robbins' pondweed
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Family: Potamogetonaceae · Type: Herb · Native
Conservation status: CNPS 2B.3
Potamogeton robbinsii (Robbins' pondweed) is a native California herb in the Potamogetonaceae family, recognized by 2-ranked stiff leaves with many fine veins absolutely distinctive.
Robbins' pondweed is a native perennial aquatic plant found in the Klamath Ranges and central Sierra Nevada Mountains in deep water and lake habitats at elevations of 1,600 to 3,300 meters. Flowering from August to September, this submersed plant produces small, inconspicuous flowers in compact clusters less than 2 centimeters long. Growing with flexible stems up to 200 centimeters long and many branches, it forms dense underwater meadows with multiple cylindrical stems. Its leaves are narrow and linear to lanceolate, typically 3 to 4 millimeters wide, stiff and arranged in two ranks with 20 to 60 fine veins, and finely serrated along the edges. The plant's distinctive stipules are fibrous, fused to the leaf base, and range from green-brown to white, often shredding at the tips.
Identification and appearance
Key characters: 7 sympatric species; 2-ranked stiff leaves with many fine veins absolutely distinctive
Habitat and range
Habitat: Deep water, lakes
Elevation: 1600-3300 m
California counties: Inyo, Madera, Siskiyou, El Dorado, Alpine, Tuolumne, Mono, Fresno, Santa Barbara
Outside California: to Alaska, eastern United States
Bloom period
Potamogeton robbinsii blooms Aug-Sep.
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 robbinsii native to California?
Yes. Potamogeton robbinsii is native to California (recorded as native).
When does Potamogeton robbinsii bloom?
Potamogeton robbinsii blooms Aug-Sep.
Where in California does Potamogeton robbinsii grow?
Potamogeton robbinsii occurs in Inyo, Madera, Siskiyou, El Dorado, Alpine, Tuolumne, Mono, Fresno and other counties, at elevations of 1600-3300 m.
What plant family does Potamogeton robbinsii belong to?
Potamogeton robbinsii is in the Potamogetonaceae family, genus Potamogeton.
Is Potamogeton robbinsii rare or endangered?
Potamogeton robbinsii carries California Rare Plant Rank 2B.3, state rank S3.
Related species
Other California species in the same genus, family, or bioregion.
- Potamogeton sp. — Pondweed
- Potamogeton zosteriformis — Eel-grass pondweed
- Potamogeton alpinus — Alpine pondweed
- Potamogeton amplifolius — Broad-leaved pondweed
- Potamogeton berchtoldii — Narrow leaved pondweed
- Potamogeton crispus — Crisp-leaved pondweed
- Potamogetonaceae sp. — Pondweed family
- Stuckenia filiformis subsp. alpina — Slender-leaved pondweed
Sources: Jepson eFlora · CNPS Rare Plant Inventory · Index of California Plant Names · 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.