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Aquatic and Wetland Vascular Plants of the Northern Great Plains

55. Potamogetonaceae, the Pondweed Family

1. Potamogeton L. -- Pondweed

6. Potamogeton filiformis Pers. -- Slender pondweed


Stems subterete, to 1 mm wide, branching dichotomously from the base, mostly unbranched above, 1-5 dm long. Leaves all submersed, filiform to narrowly linear, 5-12 cm long, 0.2-2 mm wide, 1(3)-nerved, acute to obtuse; stipules adnate to the base of the leaf blade, 1-4 cm long, forming a tight sheath around the stem, the free portion projecting as a ligule 2-10 mm long. Spikes elongate, 1-5 cm long, with 2-5 remote to adjacent whorls of flowers; peduncles slender, 2-15 cm long. Fruits olivaceous, obovoid, 2-3 mm long, rounded on the back, the beak flat, inconspicuous. Jul--Aug. Shallow standing or flowing water; uncommon and local in our region, mostly in the w part; (Circumboreal, in N.Amer. s to ME, PA, MI, MN, NE, CO, AZ and CA; also Africa and Australia).

Many previous records of P. filiformis in this region were based on misidentified P. pectinatus.

GIF- Distribution Map

Map key


Previous Section -- Potamogeton epihydrus Raf. -- Ribbonleaf pondweed
Return to Family -- Potamogetonaceae - The Pondweed Family
Next Section -- Potamogeton foliosus Raf. -- Leafy pondweed

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Menlo Park, CA [caww55]