Northern Prairie Wildlife Research Center
Northeast Wetland Flora
Field Office Guide to Plant Species
Potamogeton gramineus L.
- Family: Pondweed (Potamogetonaceae)
- Flowering: July-September
- Field Marks: The floating leaves of this species are elliptic to ovate and rounded at the tip,
while the submersed leaves are narrowly elliptic to oblanceolate and pointed at the tip. The
obovoid fruits are strongly keeled.
- Habitat: Ponds, lakes, streams.
- Habit: Aquatic perennial from red-spotted rootstocks.
- Stems: Much branched, very slender, smooth.
- Leaves: Of 2 kinds: floating leaves elliptic to ovate, rounded at the tip, tapering or rounded at the base, leathery, up to 2 1/2 inches long, up to 1 1/2 inches wide, with a stalk up to 6 inches long; submersed leaves narrowly elliptic to oblanceolate, pointed at the tip, tapering to the sessile base, finely toothed, up to 2 1/2 inches long, up to 1/3 inch wide.
- Flowers: Crowded into spikes, the spikes up to 1 1/2 inches long, 1/4-1/2 inch thick; flowers sessile or very short-stalked.
- Sepals: 4, green, free from each other, up to 1/8 inch long.
- Petals: 0.
- Stamens: 4.
- Pistils: 4, free from each other, smooth.
- Fruits: Achenes obovoid, prominently keeled, greenish, up to 1/8 inch long, with a short, curved beak.
- Notes: Waterfowl eat the achenes.
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