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Aquatic and Wetland Vascular Plants of the Northern Great Plains

55. Potamogetonaceae, the Pondweed Family

1. Potamogeton L. -- Pondweed

5. Potamogeton epihydrus Raf. -- Ribbonleaf pondweed

Stems somewhat flattened, 1-2 mm thick, simple or sparingly branched, to 2 m long. Submersed leaves linear, ribbonlike, 5-20 cm long, 3-6(10) mm wide, 5- to 7(13)-nerved, with a cellular-reticulate strip on each side of the midvein forming a conspicuous median band 1-2 mm wide, acute to rather blunt, slightly tapered to the sessile base. Floating leaves usually present, elliptic or oblong-elliptic, (2)3-8 cm long, (5)10-20 mm wide, mostly 11- to 25-nerved, obtuse to bluntly mucronate at the tip, tapering to flattened petioles which are usually shorter than the blades; stipules free, rather membranous and delicate, 1-3 cm long. Spikes dense, cylindric, usually 2-4 cm long; peduncles about as thick as the stem, 3-8 cm long. Fruits olivaceous to brown, broadly and obliquely obovate, concave on the sides, 2-3 mm long; dorsal keel prominent, thickly winged; lateral keels low, mostly rounded; beak minute. Jul--Sep. Stream pools and lakes in the Black Hills; (Newf. and Que. to AK, s to GA, MO, SD, CO, ID and CA).
GIF- Distribution Map

Map key

Previous Section -- Potamogeton diversifolius Raf. -- Waterthread pondweed
Return to Family -- Potamogetonaceae - The Pondweed Family
Next Section -- Potamogeton filiformis Pers. -- Slender pondweed

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