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

Potamogeton nodosus Poir.
long-leaved pondweed (longleaf pondweed)
Potamogetonaceae (Horned pondweed family)

Introduction to Vascular Plants
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Distribution of Potamogeton nodosus
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Species Information

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Perennial, aquatic herb from strong rhizomes; stems up to 150 cm long, simple or branched.
Submersed leaves narrowly lanceolate, flat, leathery, dark green, 4-15 cm long, 1-4 cm wide, with 7 to 15 veins, the tips blunt, tapering into long stalks greater than 2 cm long, the stipules 3-6 cm long, delicate and early decaying; floating leaves lanceolate to elliptical, 5-20 cm long, 2-7 cm wide, leathery, long-stalked, the tips pointed, tapering at the bases.
Inflorescence spikelike, the spikes 3-6 cm long, with 10 to 16 whorls of flowers, the stalks thick, inflated.
Achenes, widely egg-shaped or almost globe-shaped, 3.5-4 mm long, 2.5-3 mm wide, the beaks short, the keels strongly developed.
Stem anatomical characters Interlacunar and subepidermal bundles absent, pseudohypodermis absent, endodermis of O-cells with variably thickened cell walls and approaching U-cells.

Source: The Illustrated Flora of British Columbia

USDA Species Characteristics

Flower Colour:
Blooming Period:
Mid Summer
Fruit/Seed characteristics:
Colour: Brown
Present over the Summer
Source:  The USDA

Habitat / Range

Lakes and sloughs of the lowland zone; rare in the lower Fraser River Valley and in the Okanagan Valley, doubtful elsewhere; cosmopolitan with disjunctions, E to PQ and NB and S to ME, MA, PA, NC, FL, MS, TX, NM, AZ and CA; Eurasia, Mexico, S America, Africa.

Source: The Illustrated Flora of British Columbia


Ecological Framework for Potamogeton nodosus

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) 390 717 1045
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]
7 7 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: CWH(1), IDF(1)


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 americanus Cham. & Schltdl.
Potamogeton fluitans Roth

Taxonomic and Nomenclatural Links

Additional Photo Sources

General References