What does hydrilla look like compared to other submerged weeds?

Hydrilla is defined by whorls of 4-8 pointed, strap-like leaves with visibly serrated (toothed) edges, and it produces subterranean potato-like tubers.

How do I know if a submerged weed is invasive?

Invasive submerged weeds often grow rapidly, forming dense monocultures that reach the water surface and shade out other plants. Visual identification using leaf whorls and margins is critical to confirm the species.

What is the most common native lookalike to hydrilla?

Elodea canadensis (American waterweed) is the most common native lookalike. It typically has 3 leaves per whorl and lacks prominent serrations.

Back to Hydrilla Identification

Submerged Aquatic Weed Identification Guide

A comprehensive visual ID guide for submerged aquatic weeds. Learn what hydrilla looks like compared to other common invasive and native water plants.

Submerged Aquatic Weed Identification

Submerged aquatic weeds live entirely under the water surface, though they may form dense canopies or produce small flowers that float on top. Knowing exactly "what does hydrilla look like" compared to the broad spectrum of submerged plants is essential for effective lake management.

Misidentifying a native, beneficial plant as an invasive weed can lead to harmful, unnecessary chemical treatments. Conversely, failing to recognize an early infestation of Hydrilla verticillata can allow it to overwhelm an ecosystem.

The "Big Three" Whorled Submerged Plants

The most common identification confusion occurs between three plants that share a similar structural appearance: a central stem with small, strap-like leaves arranged in whorls (circles) around the stem nodes.

Hydrilla (Invasive)

4 to 8 leaves per whorl
Visibly serrated (toothed) margins
Rough texture
Produces tubers on roots

Egeria (Invasive)

4 to 6 leaves per whorl
Smooth or very finely serrated margins
Larger, robust stems and leaves
No tubers

Elodea (Native)

Usually 3 leaves per whorl
Smooth margins
Softer, smaller leaves
No tubers

Other Common Submerged Weeds

Beyond the whorled-leaf varieties, several other submerged plants are frequently encountered:

Eurasian Watermilfoil (Invasive)

Instead of simple strap-like leaves, milfoil has finely divided, feather-like leaves usually arranged in whorls of four. Compare Hydrilla vs Milfoil.

Coontail (Native)

A rootless plant with stiff, branching, Y-shaped leaves that bunch heavily at the tips resembling a raccoon's tail. Compare Hydrilla vs Coontail.

Curly-leaf Pondweed (Invasive)

Leaves are arranged alternately (not in whorls) and have a distinctive lasagna-noodle wavy, crinkled edge. Compare Hydrilla vs Pondweed.

Key Steps for Field Identification

Extract a clean sample: Rinse mud and algae off the stem so you can clearly see the leaf nodes.
Check the leaf arrangement: Are leaves alternate, opposite, or in a circular whorl?
Count the whorl: If whorled, count the number of leaves at a single node. 4+ indicates possible Hydrilla or Egeria.
Inspect the margins: Use a magnifying glass if necessary. Distinct teeth/serrations strongly indicate Hydrilla.
Check the roots: Gently dig into the sediment. The presence of potato-like tubers is the definitive identifier for Hydrilla.

Deep Dive Comparisons

Frequently Asked Questions About Submerged Aquatic Weed Identification Guide

References

Information presented on this page is supported by peer-reviewed research, federal agencies, and state resource management programs.

U.S. Geological Survey (USGS) – Nonindigenous Aquatic Species Databasehttps://nas.er.usgs.gov
U.S. Army Corps of Engineers – Aquatic Plant Control Research Programhttps://www.erdc.usace.army.mil
NOAA Aquatic Invasive Species Programhttps://www.noaa.gov