Flatstem Pondweed (Potamogeton zosteriformis)

Flatstem Pondweed (Potamogeton zosteriformis) 

The Flatstem Pondweed (Potamogeton zosteriformis) is of the order Najadales and Pondweed Family (Potamogetonaceae). The order name refers to a water nymph. The family and genus name is Greek for "river neighbor." The species name is Greek for "girdle-like." This plant can be several yards (meters) long and grow in water as much as four yards (3.6 meters) deep. As the common name implies, the stems of this plant are relatively flat. The photograph above was taken on French Hill Pond on September 18, 2010.

The leaves on this plant are totally submerged. There are no floating leaves. The leaves are alternately arranged, linear, entire, pointed and have a prominent midvein .

The flower of the Flatstem Pondweed (Potamogeton zosteriformis) is a small green to brown spike just above the water on a stem. This plant flowers from summer until fall. The fruit is an oval, dry seed with a sharp, narrow, dorsal ridge.

The root system is marginally rhizomic.  It will generally propagate by seeds.

 The Flatstem Pondweed (Potamogeton zosteriformis) is similar to the Bluntleaf Pondweed (Potamogeton obtusifolius) and slender pondweeds but is larger.


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