Nuisance Aquatic Plant & Weed Identification Guide
Knowing how to identify pond weeds is the most important step in selecting the right treatment. Plants that look similar often require completely different herbicides, and applying the wrong product wastes money and can make problems worse. Use this guide to identify the aquatic plants in your pond or lake, then follow the treatment recommendations for your specific species.
Not sure what you're looking at? Send us a photo and our aquatic plant experts will identify it for you — free of charge.
Quick Navigation
- Submerged Plants — Underwater, rooted or free-floating below the surface
- Floating Plants — On the water surface, free-floating or rooted
- Emergent & Shoreline Plants — Rooted in shallow water or shore, extending above the surface
- Algae & Algae-Like Organisms — Microscopic to large, not true plants
- How to Identify Your Plant
- Treatment Products Quick Reference
- Regional Guide by EPA Ecoregion
- Ecological Benefits & Balanced Management
How to Identify Your Plant
Aquatic plants are classified by where they grow in the water column:
Submerged Plants grow entirely or mostly underwater. Stems are typically limp and flexible. You'll often notice them when they reach the surface or when wading/boating. Examples: hydrilla, coontail, watermilfoil.
Floating Plants sit on the water surface. Some are free-floating (duckweed, water hyacinth) while others are rooted to the bottom with leaves that float on the surface (water lilies, watershield).
Emergent Plants are rooted in shallow water or wet soil at the pond's edge, with stems and leaves extending well above the surface. Examples: cattails, phragmites, water primrose.
Algae range from microscopic organisms that turn water green to filamentous mats to large branching forms. They're not true plants but are managed similarly.
Tip: Many ponds have more than one type of aquatic plant. Identify each species separately — they may require different treatments.
Submerged Plants
These plants grow entirely or mostly below the water surface. Click any species name for a full identification guide with photos, treatment recommendations, and ecological profile.
Tier 1 — Most Common & Impactful
| Species | Scientific Name | Key Feature |
|---|---|---|
| Hydrilla | Hydrilla verticillata | Whorls of 4–8 leaves, serrated margins, midrib spines |
| Eurasian Watermilfoil | Myriophyllum spicatum | Feathery leaves, 12–21 leaflet pairs, limp when removed |
| Coontail (Hornwort) | Ceratophyllum demersum | Rootless, forked leaves, bushy "raccoon tail" tips |
| Curly-Leaf Pondweed | Potamogeton crispus | Wavy/crinkled leaf margins, grows under ice |
| Elodea | Elodea canadensis | Whorls of 3, smooth margins, smaller than hydrilla |
| Egeria (Brazilian Elodea) | Egeria densa | Whorls of 4–6, larger than elodea, white flowers |
| American Pondweed | Potamogeton nodosus | Both submerged and floating leaves, leathery floating pads |
Tier 2 — Regionally Significant
| Species | Scientific Name | Key Feature |
|---|---|---|
| Sago Pondweed | Stuckenia pectinata | Thread-like leaves, banana-shaped tubers |
| Bladderwort | Utricularia spp. | Tiny bladder traps on leaves, carnivorous |
| Cabomba (Fanwort) | Cabomba caroliniana | Fan-shaped, finely divided leaves in pairs |
| Southern Naiad | Najas guadalupensis | Opposite toothed leaves, bushy branching |
| Brittle Naiad | Najas minor | Extremely fragile stems, strongly toothed margins |
| Hygrophila | Hygrophila polysperma | Opposite leaves, square stems |
Tier 3 — Localized
| Species | Scientific Name | Key Feature |
|---|---|---|
| Northern Watermilfoil | Myriophyllum sibiricum | Feathery leaves, fewer leaflets (5–12) than Eurasian |
| Illinois Pondweed | Potamogeton illinoensis | Broad elliptical submerged leaves, prominent veins |
| Horned Pondweed | Zannichellia palustris | Threadlike leaves, distinctive horn-shaped seeds |
| Vallisneria (Tape Grass) | Vallisneria americana | Long ribbon-like leaves from basal rosette |
| Water Stargrass | Heteranthera dubia | Narrow grass-like leaves, yellow star-shaped flowers |
Floating Plants
These plants float on the water surface — either free-floating or rooted with floating leaves.
Tier 1 — Most Common & Impactful
| Species | Scientific Name | Key Feature |
|---|---|---|
| Duckweed | Lemna minor | Tiny oval fronds (1/16–1/4 inch), single root |
| Watermeal | Wolffia spp. | World's smallest plant — grain-of-sand sized, no root |
| Water Hyacinth | Eichhornia crassipes | Glossy round leaves, bulbous petioles, lavender flowers |
| Water Lilies & Spatterdock | Nymphaea / Nuphar spp. | Large floating pads with V-notch, showy flowers |
Tier 2 — Regionally Significant
| Species | Scientific Name | Key Feature |
|---|---|---|
| Water Lettuce | Pistia stratiotes | Velvety rosettes resembling floating lettuce |
| Watershield | Brasenia schreberi | Oval floating leaves with slimy gelatinous underside |
| Giant Salvinia | Salvinia molesta | Paired leaves, "egg-beater" hairs, mats several feet thick |
| Common Salvinia | Salvinia minima | Smaller paired leaves, flat hairs (not egg-beater) |
| Floating Heart | Nymphoides spp. | Mini lily pads, fringed yellow or white flowers |
| Water Chestnut | Trapa natans | Floating rosette, hazardous spiny four-barbed seeds |
Tier 3 — Localized
| Species | Scientific Name | Key Feature |
|---|---|---|
| European Frog's-bit | Hydrocharis morsus-ranae | Small heart-shaped leaves, free-floating, Great Lakes region |
| Mosquito Fern | Azolla spp. | Tiny, velvety, green to reddish-brown mats |
| Waterspangles | Salvinia oblongifolia | Small floating fern clusters, oblong paired leaves |
Emergent & Shoreline Plants
These plants are rooted in shallow water or wet soil, with stems and leaves extending above the water surface.
Tier 1 — Most Common & Impactful
| Species | Scientific Name | Key Feature |
|---|---|---|
| Cattails | Typha spp. | Tall sword-like leaves, iconic brown cylindrical flower spike |
| Phragmites (Common Reed) | Phragmites australis | Very tall (10+ feet), feathery plume, dense monocultures |
| Creeping Water Primrose | Ludwigia spp. | Trailing stems, shiny leaves, bright yellow 5-petaled flowers |
Tier 2 — Regionally Significant
| Species | Scientific Name | Key Feature |
|---|---|---|
| Parrot Feather | Myriophyllum aquaticum | Stiff, waxy, feathery emergent leaves, bright green |
| Dollar Weed (Pennywort) | Hydrocotyle spp. | Round coin-shaped leaves, stalk attaches to center |
| Alligator Weed | Alternanthera philoxeroides | Hollow stems, opposite leaves, white clover-like flowers |
| Giant Reed | Arundo donax | Very tall (15–30 ft), bamboo-like, broad clasping leaves |
Tier 3 — Localized
| Species | Scientific Name | Key Feature |
|---|---|---|
| Flowering Rush | Butomus umbellatus | Triangular leaf cross-section, pink flower umbrella |
| Purple Loosestrife | Lythrum salicaria | Tall purple-magenta flower spikes, square stems |
| Smartweed | Persicaria spp. | Papery sheaths at nodes, pink/white flower spikes |
| American Lotus | Nelumbo lutea | Very large cupped leaves above water, yellow flowers |
| Elephant Ear | Colocasia esculenta | Very large arrow-shaped leaves, tropical appearance |
| Bulrush | Schoenoplectus spp. | Tall round/triangular stems, drooping flower clusters |
| Pickerelweed | Pontederia cordata | Heart-shaped leaves, violet-blue flower spikes |
| Arrowhead | Sagittaria spp. | Arrow-shaped leaves, white 3-petaled flowers |
| Rush | Juncus spp. | Stiff round solid stems, dense clumps |
| Sedges | Carex spp. | Triangular stems ("sedges have edges"), dense tufts |
| Horsetail | Equisetum spp. | Jointed hollow stems, rough texture, spore cones |
| Watercress | Nasturtium officinale | Small rounded compound leaves, white flowers, peppery |
| Water Willow | Justicia americana | Narrow willow-like leaves, white-purple flowers |
Algae & Algae-Like Organisms
Not true plants, but the most common "weed" complaints in ponds and lakes.
| Type | Key Feature |
|---|---|
| Planktonic Algae | Microscopic — turns water uniformly green ("pea soup") |
| Filamentous Algae | Hair-like strands forming slimy, stringy mats |
| Blue-Green Algae (Cyanobacteria) | ⚠ Potentially toxic — looks like spilled green paint |
| Chara (Muskgrass) | Gritty texture, garlic odor, branching structure |
| Nitella | Soft, smooth (not gritty), no odor, clear-water indicator |
| Starry Stonewort | Star-shaped bulbils, taller than chara, Great Lakes region |
Supporting Resources
- Product Cross-Reference — Which Natural Waterscapes products treat which species
- EPA Ecoregion Guide — Species distribution by region
- Beneficial Considerations — Why some aquatic plants are valuable and how to manage selectively
Need Help?
Can't identify your plant? Take a close-up photo showing the leaves, stem, and overall growth pattern. Send it to our experts and we'll identify it and recommend treatment — free of charge.
Not sure which product to use? See our Aquatic Weed Management Guide or call us for personalized recommendations.
Natural Waterscapes — Expert Aquatic Plant Identification & Treatment Sources: Texas A&M AquaPlant | USDA PLANTS Database | EPA Ecoregions | USGS NAS