E-Flora BC: Electronic Atlas of the Flora of British Columbia

Potamogeton zosteriformis Fernald
eel-grass pondweed (flatstem pondweed)
Potamogetonaceae (Horned pondweed family)

Introduction to Vascular Plants
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Distribution of Potamogeton zosteriformis
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Species Information

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Perennial, aquatic herb from fine, tufted roots; stems up to 130 cm long, strongly compressed, flattened, branched.
All submersed, linear, the sides parallel, stiff, olive green, 10-20 cm long, 0.2-0.5 cm wide, unstalked, usually with 7 to 15 veins, attached at the nodes, tapering to pointed tips, the stipules 1.5-3.5 cm long, the margins overlapping, straight, smooth.
Inflorescence spikelike, the spikes 1.5-3 cm long, with 5 to 9 whorls of flowers, the stalks thin.
Achenes, egg-shaped, 4-5 mm long, 3-3.5 mm wide, the beaks conspicuous, the keels winged.

Source: The Illustrated Flora of British Columbia

USDA Species Characteristics

Flower Colour:
Blooming Period:
Mid Summer
Fruit/Seed characteristics:
Colour: Green
Present from Summer to Fall
Source:  The USDA

Habitat / Range

Lakes in the lowland, steppe and montane zones; frequent in BC east of the Coast-Cascade Mountains, infrequent in coastal BC; N to AK, YT and NT, E to NF and S to ME, MA, NY, VA, OH, IN, IL, IA, NE, WY, UT, ID and CA.

Source: The Illustrated Flora of British Columbia


Ecological Framework for Potamogeton zosteriformis

The table below shows the species-specific information calculated from
original data (BEC database) provided by the BC Ministry of Forests and Range.
(Updated August, 2013)

Site Information
Value / Class




Elevation (metres) 1117 1117 1118
Slope Gradient (%) 0 0 0
Aspect (degrees)
[0 - N; 90 - E; 180 - S; 270 - W]
Soil Moisture Regime (SMR)
[0 - very xeric; 4 - mesic;
8 - hydric]
8 8 8
Modal Nutrient Regime
Number of field plots
 species was recorded in:
Modal BEC Zone Class
All BEC Zones (# of stations/zone) species was recorded in: CDF(1), SBPS(3)


The climate type for this species, as reported in the: "British Columbia plant species codes and selected attributes. Version 6 Database" (Meidinger et al. 2008), is not evaluated, unknown or variable.

Synonyms and Alternate Names

Potamogeton compressus auct. non L.
Potamogeton zosterifolius subsp. zosteriformis (Fernald) Hult╬śn

Taxonomic and Nomenclatural Links

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General References