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Wisconsin Plant of the Week

Potamogeton epihydrus Raf.

Potamogetonaceae (Pondweed Family)

Common Name:

ribbon-leaf pondweed

08/18/2002

Pondweeds are perennial aquatic plants rooted in the beds of slow streams or lakes to a depth where light can still penetrate the water. About 30 species and their hybrids occur in Wisconsin and they’re a major component of aquatic habitat.  Pondweeds stabilize the bottom substrate and remove particulate matter from the water column.  Dense beds are nurseries for small fish who find cover from predators among the leaves feed on the algae and small aquatic organisms that live on the plants. Waterfowl also eat the leaves and protein-rich seeds.

All pondweed flowers are inconspicuous and in spikes.  The spikes of pondweeds with broad leaves, like ribbon-leaf pondweed, are held above the water in July and August and are wind-pollinated.

Like most aquatic plants the leaf form of pondweeds can vary with water conditions -- whether it’s still or flowing, shallow or deep.  Submerged leaves are always alternate and undivided. Some species, like ribbon-leaf pondweed, have opposite leathery floating leaves on long stalks or petioles. 

Ribbon-leaf pondweed is a short-lived native species of soft water lakes and streams that grows from rhizomes.  The submerged leaves are long, flat, attached directly to the stem and have a blunt tip. The species is easily recognized by its submerged leaves -- a row of transparent cells along either side of the mid-vein makes a light band running the length of the leaf.

The Pondweed family includes two genera -- Potamogeton and StuckeniaStuckenia, e.g. sago pondweed, differs in that it has no floating leaves, and both pollination and seed set occur under water

  • Origin of the name: Potamogeton, potamos, Gk., river; geiton, Gk., neighbor; epihydrus, Gk., above the water
  • Range:  N. Amer., s. to CA, UT, FL; Europe
  • WI Range:  More common in the northern two-thirds of the state, where pH is neutral to mildly acidic
  • Common associates: Coontail, large leaf pondweed, milfoils
  • Wetland Indicator Status: OBL
  • Coefficient of Conservatism: 8, WI; 8, MI; 10, Chicago Region
  • Related sites: Flora of North America, Potamogeton
     
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