Weed Identification


Welcome to SePRO's Aquatic Weed Identification Guide. This guide will serve as your first step toward identifying and managing your aquatic weed problem. To get started, click on whichever group of aquatic weeds to which you feel your problem weed belongs and work through the examples until you find it.



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Alternanthera philoxeroides

Alligatorweed is an emersed plant. It can grow in a variety of habitats, including dry land, but is usually found in water. It may form sprawling mats over the water or along shorelines. Alligatorweed stems are long branched, and hollow. Leaves are simple, elliptic, and have smooth margins. The leaves are the opposite. The whitish papery flowers grow on stalks. Alligatorweed flowers during the warm summer months.

Also known as: Green lead plan; pigweed

American Lotus

Nelumbo lutea

Floating leaves are circular, and are attached to stems that are anchored in the soil. The leaves create a bowl-like appearance and do not lay flat on the water surface. Yellow flowers emerge from the plant.

Also known as: Mistaken for yellow water lily.

American Pondweed

Potamogeton nodosus

American pondweed has oval-shaped leaves that spread across the water surface. The seed head extends above the water on slender stalks. American pondweed can form dense mats and block sunlight for submersed vegetation. American pondweed can be mistaken for Illinois pondweed.

Also known as: Illinois pondweed; Pondweed

American Water-willow

Justicia americana (L.) Vahl

American Water-willow is found in places with an abundant water and sunlight supply and is seen as both a shrub and a large tree. It often has multiple trunks, each with many branches coming from each. American Water-willow leaves are long and thin. The leaves are shiny green on top, and pale green on the underside and are three to five inches long and may have very fine teeth. The tree bark is dark brown or black with ridges.

Justicia americana (L.) Vahl