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Invasive Species Sheet - Curley Pondweed

Invasive Species Identification Sheet

Curley Pondweed (Potamogeton crispus L.)

Alternate Common Names: Curlyleaf Pondweed; Curly-leaved or Crispy-leaved Pondweed
- underwater plant; rooted herbaceous perennial
- mainstem flattened
- leaves parallel-veined; generally alternate; all of a similar shape, and all underwater
- leaves linear-oblong, 1 1/4"–3" long; up to 1/2" wide; margins finely and irregularly toothed
- leaves stalkless and wavy-margined (resembling a miniature, green lasagna noodle)
- plant produces extremely hard bur-like turions that are up to 2" long and consist of small, hardened leaves, typically at least 1/4" wide
  that stick out horizontally from a central stem
- flowers very small and not showy; in stiff spikes
- fruit small, hard, less than 1/4" long including the beak (it is at least 1/16" long) on the top

There are many pondweeds in New England, but Curly Pondweed is easily recognized by its leaf characteristics. Mature leaves have the crinkled, lasagna noodle-like appearance. All leaves have irregular serrations (use hand lens) on their margins and are stalkless. Curly Pondweed has been used as an aquarium plant. It may grow profusely in ponds and streams. It tolerates a variety of conditions, although it is thought to prefer alkaline or nutrient enriched water. It may be found early in the spring and reaches its peak amount of foliage in the late spring or early summer after which it dies back. When the plant dies back, the turions survive. In the fall, the turions sprout and form roots, helping the Pondweed to spread.

During the heat of the summer, native plants still growing in the water may be deprived of dissolved oxygen that
goes to break down the dead Curly Pondweed leaves.