Potamogeton amplifolius
USDA, NRCS. 2018. The PLANTS Database (http://plants.usda.gov, 28 March 2018). National Plant Data Team, Greensboro, NC 27401-4901 USA.
Illustration: USDA-NRCS PLANTS Database / USDA NRCS. Wetland flora: Field office illustrated guide to plant species. USDA Natural Resources Conservation Service.
What is Large-leaf Pondweed?
Other common spellings and names include: Big-leaved pondweed, Broad leaved pondweed, Broad-leaved pondweed, Large Leaf pondweed, Large-leaved pondweed, and Largeleaf pondweed.
Physical Characteristics
Leaves:
Submersed Leaves:
- Bright or dark green
- Almost see-through
- 3.15-7.87 inches long
- 0.79-2.95 inches wide
- Folded along middle
- Curved
- Wavy edges
- Stalks 0.39-0.79 inches long
- Many veins (27-49)
Floating Leaves:
- Often not present
- Leathery in texture
- Oval to sword shaped
- 2-4 inches long
- 1-2 inches wide
- Stalks 1.18-4 inches long
Flowers:
- Small
- Petal-like lobes
- 6 to 16 whorls
- Clustered
- Spike up from 0.5 to 3 inches long
- Stalks up to 2-5 inches long
- 4 petals, sepals, and stamens
- Above water
Fruit:
- Small
- Dry
- One seeded
- 0.12-0.2 inches long
- Flat sides
- Orange or pinkish when ripe
Stem:
- Not branching
- Up to 0.12 inches thick
- Up to 15 feet long
- Creeping rhizomes
Roots:
- Fibrous
Where Does it Grow?
Large-leaf pondweed can be found in slightly acidic, slow-moving streams, rivers, lakes and farm ponds throughout the United States and Canada, but has not been documented in Texas. Compared to other pondweeds, this species can be found in deeper waters.
Pros and Cons of Large-leaf Pondweed
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.