Flat-Stem Pondweed

(Potamogeton zosteriformis, Potamogeton compressus)


Flat-stem pondweed has both a flat stem and flat leaves with no floating leaves.


Flat-stem pondweed has no floating leaves. The flat submersed leaves spiral around the stem and are light to dark green with a yellow midvein that has many parallel veins. These veins make the leaf more stiff and rigid than other aquatic plant leaves. Flat-stem pondweed leaves have a pointed tip, are four to eight inches long, and less than a quarter inch wide. Stems are also flat (hence the name) and angular-looking, growing two to four feet long. The only part of the plant that breaks through the surface of the water is a flower spike that sticks up one-half to one inch or so. There are five to nine whorls of greenish to whitish flowers per spike and a group of tightly packed leaves around it.

Flat-stem pondweed thrives in many conditions, which may be due in part to its high antimicrobial properties. The plant looks angular because the branches on the stem can be as thick as the stem itself. Some ducks feast on flat-stem pondweed, as well as a few muskrats, beavers, deer, and moose.


Flat-stem pondweed can be found in the northern half of the United States.


Winter buds, rhizomes