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Western Wetland Flora

Field Office Guide to Plant Species

Long-leaf Pondweed
Potamogeton nodosus Pair.

JPG -- Species Photo JPG -- Distribution Map

Family: Pondweed (Potamogetonaceae)
Flowering: June-August
Field Marks: This pondweed has both submersed and floating leaves. The submersed leaves do not clasp the stem and are 1/2-1 1/2 inches wide and are on stalks at least 1 inch long. The elliptic to oblong floating leaves are 2-5 inches long and 1-
Habitat: Quiet waters of ponds, lakes, streams, and ditches.
Habit: Partially submersed perennial with spreading rhizomes.
Stems: Rather stout, branched or unbranched.
Leaves: Of two kinds: submersed leaves linear-lanceolate, 4-8 inches long, 1/2-1 1/2 inches wide, thin and very weak, with 7-15 veins, with a leaf stalk at least 1 inch long; floating leaves elliptic to oblong, 2-5 inches long, 1-2 inches wide, with 10-20 veins, on stalks up to 10 inches long.
Flowers: Several crowded into spikes, the spikes up to 2 1/2 inches long, on stout stalks up to 6 inches long.
Sepals: 4, greenish, 1/8-1/6 inch long.
Petals: 0.
Stamens: 4.
Pistils: 4, each with a superior ovary.
Fruits: Achenes obovoid, asymmetrical, up to 1/6 inch long, up to 1/8 inch wide, with a short beak at the tip.
Notes: The achenes are eaten by waterfowl.

Previous Species -- Floating-leaf Pondweed (Potamogeton natans)
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Next Species -- Sago Pondweed (Potamogeton pectinatus)

U.S. Department of the Interior | U.S. Geological Survey
URL: http://www.npwrc.usgs.gov/resource/plants/florawe/species/4/potanodo.htm
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Page Last Modified: Saturday, 02-Feb-2013 06:25:22 EST
Reston, VA [vaww55]