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Western Wetland Flora

Field Office Guide to Plant Species

White-stem Pondweed
Potamogeton praelongus Wulfen

JPG -- Species Photo JPG -- Distribution Map

Family: Pondweed (Potamogetonaceae)
Flowering: May-July
Field Marks: The leaves of this aquatic pondweed are all submersed and clasp the stem at the base. The stems are usually zigzag and the achenes are at least 1/4 inch long.
Habitat: Deep water in lakes and streams.
Habit: Submersed perennial with a stout rhizome.
Stems: Stout, zigzag, branched, olive-green to whitish, up to 1 foot long, smooth.
Leaves: Alternate, simple, all submersed, oblong-lanceolate, up to 10 inches long, up to 1 1/2 inches wide, more or less rounded at the tip and forming a small hood, rounded to heart-shaped at the base and clasping the stem, smooth: stipules up to 4 inches long, whitish.
Flowers: Crowded into spikes up to 2 1/2 inches long, the spikes on stalks up to 1 1/2 feet long.
Sepals: 4, green, free from each other, up to 1/6 inch long.
Petals: O.
Stamens: 4.
Pistils: 4, free from each other, smooth.
Fruits: Achenes obovoid, up to 1/4 inch long, up to 1/6 inch wide, smooth. with a short, persistent beak at the tip.
Notes: The achenes are eaten bv waterfowl.

Previous Species -- Sago Pondweed (Potamogeton pectinatus)
Return to Species List -- Group 4
Next Species -- Small Pondweed (Potamogeton pusillus)

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Page Last Modified: Saturday, 02-Feb-2013 06:25:24 EST
Menlo Park, CA [caww54]