Aquatic Weed Identification Guide

Aggressive invasive that can grow an inch per day. Forms dense mats from bottom to surface. Leaves in whorls of 4–8 with serrated edges and a distinctive midrib spine.

Feathery, finely divided leaves with 12–21 pairs of leaflets. Spreads aggressively through fragmentation. Commonly confused with coontail and fanwort.

Free-floating with no root system. Forked, rigid leaves arranged in whorls become denser toward stem tips — like a raccoon tail. Stays green year-round.

Bright green leaves in whorls of 3 along stems up to 4 feet. One of the few pond plants that stays green through winter. Provides year-round fish habitat.

Looks like a larger, more robust version of native elodea. Leaves in whorls of 4–6 (vs. 3 in native elodea). Produces white flowers above the surface.

Fan-shaped, finely divided leaves opposite on stems. Often has reddish stems. Commonly confused with milfoil, but fanwort leaves spread like a fan rather than feather.

Elongated floating leaves connected to stems up to 6 feet long. Thin submerged leaves along the stem. Important spawning cover for largemouth bass.

Wavy, lasagna-like leaves that stay submerged. Unusual growth cycle — actively grows in fall and winter, dies back in July. Leaves do not float like American pondweed.

Very thin, thread-like leaves that fan out from the stem. Grows in water up to 8 feet deep. One of the trickier species to positively identify. Excellent waterfowl food.

Slender, opposite leaves on branching stems. Easily fragments and can spread rapidly. Provides excellent cover for fish fry but can become problematic in nutrient-rich ponds.

Free-floating carnivorous plant with tiny bladder-like traps that capture aquatic invertebrates. No roots. Yellow flowers above water. Can form dense surface mats.

Bright green feathery leaves that extend above the water surface — distinct from other milfoils. Popular in aquariums but highly invasive in natural waterways.

Technically a macroalgae, not a true plant — but universally mistaken for one. Gritty texture, garlic-like smell. Often beneficial: stabilizes sediment and reduces nutrient availability.

The smallest flowering plants on earth. Duckweed: ¼–½" with tiny roots. Watermeal: pinhead-sized, no roots. One plant becomes a billion in 30 days. Often mistaken for algae.

Round floating pads with a characteristic slit. White or yellow flowers. Rooted in sediment with stems reaching the surface. Provide shade and fish cover but can overtake shallow ponds.

Heart-shaped floating leaves with a deep notch. Yellow globe-shaped flowers. Thick rhizomes. Often confused with water lilies but leaves are thicker and more leathery.

Small oval floating leaves with a thick, gelatinous slime coating the underside and stem. No slit in the leaf like water lilies. Purple flowers.

Free-floating with bulbous, spongy stems and lavender flowers. Can double its population in two weeks. Regulated or prohibited in many states.

Free-floating rosettes of light green, velvety leaves that look like small heads of lettuce. Long feathery roots dangle beneath. Reproduces by stolons.

Tiny free-floating fern often confused with duckweed. Turns reddish-brown in fall and high light. Overlapping scale-like leaves. Fixes nitrogen from the air — unique among aquatic plants.

Free-floating fern with paired oval leaves covered in water-repellent hairs. Giant salvinia (S. molesta) is federally listed as a noxious weed. Can double biomass in days.

Tall, sword-like leaves with the iconic brown seed head. Native T. latifolia is important wetland habitat, but invasive T. angustifolia and hybrids spread aggressively through rhizomes.

Tall grass reaching 15+ feet with feathery plume seed heads. Invasive subspecies forms dense monocultures that crowd out native vegetation. Spreads by rhizomes and stolons.

Stems creep up to 15 feet across the surface from shoreline. Small yellow 5-petal flowers. Biomass can double in 3–7 days. Labeled a noxious weed in some states.

Round, scalloped-edge leaves on stalks from creeping stems. Can spread 7+ inches per day. Floating mats break free and drift. Provides habitat for aquatic life but overtakes shorelines quickly.

Opposite, lance-shaped leaves on hollow stems. Small white clover-like flowers. Grows on land and in water. Forms dense mats that impede water flow and displace native species.

Aggressive perennial grass with stiff, sharp-tipped rhizomes that "torpedo" through soil and pond liners. Extremely difficult to eradicate. Common in the southern US from Texas to Florida.