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Waterthread Pondweed

Potamogeton diversifolius

Variable-leaf Pondweed Location in US
Variable-leaf Pondweed Location in Southeast US

Variable-leaf pondweed diagram

USDA, NRCS. 2018. The PLANTS Database (http://plants.usda.gov, 28 March 2018). National Plant Data Team, Greensboro, NC 27401-4901 USA.
Illustration courtesy of University of Florida/IFAS Center for Aquatic and Invasive Plants. Used with permission.

What is Waterthread Pondweed?

Physical Characteristics

Leaves:

Submersed Leaves:

  • Thin and Straight
  • Pale green
  • Mostly 0.78-2.5 inches long
  • 0.02-0.06 inches wide
  • Slightly reducing in thickness from an immobile base
  • Midrib usually bordered by 1-4 rows of cavities
  • Peduncles 0.02-0.16 inches long from axils

Small Leaves:

  • Delicately fibrous
  • Growing from base of large leaf blade

Floating Leaves:

  • Leather texture
  • Oval- or elliptical- shaped
  • Rounded at base
  • Leaf stalks usually shorter than blades
  • Blades 1.5 inches long & 0.78 inches wide
  • Peduncles usually slender, often club-shaped
  • Peduncles 0.08-1.19 inches long from axils
  • Peduncles grow upward or arching

Small Leaves:

  • Free from leaf stalks
  • Up to 0.25 inches long
  • Delicately fibrous
  • Long-lived

Flowers:

Submersed Spikes:

  • Few flowers
  • Almost spherical

Emersed Spikes:

  • 0.2-0.78 inches long
  • Flowers nearly immobile
  • Fruit 0.13-0.16 inches wide

Fruit:

  • Almost disk-shaped
  • Sides flattened or slightly curving inward
  • 0.02-0.03 inches in diameter

Stem:

  • Horizontal root branching
  • Threadlike
  • Cylindrical

Roots:

  • Rooting at nodes

Where Does it Grow?

Waterthread pondweed can be found in pools, tanks and small streams.

Pros and Cons of Waterthread Pondweed

Waterthread pondweed seeds are consumed by waterfowl. Submerged portions of all aquatic plants provide habitats for many micro and macro invertebrates. These invertebrates in turn are used as food by fish and other wildlife species (e.g. amphibians, reptiles, ducks, etc.). After aquatic plants die, their decomposition by bacteria and fungi provides food (called “detritus”) for many aquatic invertebrates.

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Photo Credits: The majority of the aquatic plant line drawings are the copyright of the University of Florida Center for Aquatic Plants (Gainsville). They are used with permission.

Aquatic plant photographs were provided by David Bayne, Jim Davis, Kelly Duffie, Billy Higginbotham, Michael Masser, John Clayton, Chetta Owens, Diane Smith, Joe Snow, Don Steinbach, Bridget Robinson Lassiter and Peter Woods.

You may use these photos, so long as you give credit to AquaPlant.

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