Narrow-leaf Pondweeds (Potamogeton zosteriformes, Potamogeton foliosus, Potamogeton pectinatus)
Common names: Flat-stemmed, leafy, and sago pondweeds.
Location: Grow below water surface; are firmly rooted; have branched, slender stems; have grasslike, narrow leaves; may have flowers or seeds extending above water surface; are limp when out of the water.
Hints to identify: Most narrow-leaf pondweeds have no floating leaves----it is only the seeds of some types that reach or extend above the surface. Sago pondweed has stiff, threadlike leaves that appear bushy and are alternately arranged on one stem; spreading leaves in the water resemble a fan; small, pebble-sized fruits are spaced on the stem and emerge from the water.
Importance of plants: Provide some cover for bluegills, perch, northern pike, and muskellunge, though these fish prefer broad-leaf pondweeds; good cover for walleye; provide food for waterfowl; support aquatic insects and many other small animals that fish and ducklings eat. Swans, geese, and diving ducks such as canvasbacks favor the tubers and seeds of sago pondweed.
Management strategy: See DNR regulations. Removing narrow-leaf pondweeds may allow less-desirable plants such as curlyleaf pondweed or Eurasian watermilfoil to move in. If control is absolutely necessary, try hand-pulling, raking, or underwater cutting. Aquatic herbicides can be an effective control method.