Northern Prairie Wildlife Research Center
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.
Previous Section -- Potamogeton epihydrus Raf.
-- Ribbonleaf pondweed
Return to Family -- Potamogetonaceae - The
Next Section -- Potamogeton foliosus Raf. -- Leafy