European frog-bit is a free-floating annual. The leaves are leathery and round with undersides that may be dark purple. White flowers with yellow centers bloom in the summer. The leaf stem of European frog-bit lacks a midline groove which distinguishes it from its native look-alike American frog-bit, Limnobium spongia.
Water chestnut is a fast-growing, floating annual that can grow to 16 feet. The most distinctive trait of this plant is its thorny nutlets.
Brittle naiad is an herbaceous annual that grows in dense clusters. Its leaves have visible serrations and are long, pointed, and oppositely arranged on highly branched stems. The plant can reproduce from stem fragments or from small seeds which grow along its stem.
Brazilian elodea is a submerged perennial that looks similar to American waterweed (Elodea canadensis), a common native aquatic plant. Brazilian elodea has finely toothed leaves that are bright green, bushy, and usually arranged in whorls of four around the stem. The plant has round stems that can grow in water up to 20 feet deep and often branches near the surface. It reproduces via plant fragmentation.
Hydrilla is a submerged perennial that looks similar to American waterweed (Elodea canadensis), a common native aquatic plant.
Fanwort is a submerged perennial with fan-like leaves that are branched and attached to the stem on petioles, appearing whorled. Flowers are small, white, and emergent in late summer. Reproduction can occur by seed or fragmentation.
Eurasian watermilfoil is a submerged perennial that looks like many native aquatic plants, including native milfoil species.
Zebra mussels are filter-feeding freshwater bivalve mollusks. Zebra mussels are small, ¼” to 1 ½” long, and D-shaped with light and dark brown stripes.
Curly-leaf pondweed is a submerged perennial that resembles many native pondweeds. Care must be taken to correctly identify this species. Rigid, reddish-green, oblong leaves have distinct, finely toothed, wavy edges. The plant’s flat, reddish-brown stem grows from one to 16 feet. Most reproduction is from winter buds, called turions.