Stem: Long, slender, generally branched. Common waterweed is more sparingly branched than Nuttall's waterweed.

Flower: Often does not produce flowers. Small (8 mm across), white flowers occur at the ends of long, thread-like stalks and have 3 petals and usually 3 sepals. Male and female flowers occur on separate plants, but male flowers are rarely produced. Blooms from July to September. Common: sepals to 5 mm long, petals on male flowers only to 5mm. Nuttall’s: sepals to 2 mm long, petals tiny (0.5mm) or absent. Male flowers detach and become free-floating.

Fruit: Capsules approximately 6 mm long, seeds about 4 mm long, but because of a shortage of male plants, seeds are seldom produced.

Root: Tufts of fibrous roots from nodes along the stem.

Propagation: Stem fragments, overwintering buds, and rarely by seeds. 

Importance of plant: Food and habitat for fish, waterfowl, other wildlife. Used in cool water aquariums. Common waterweed is a nuisance in Europe and New Zealand where it is not native.

Distribution:  Common: throughout most of the U.S. Nuttall's: occasionally in the Northwest and California. More common in eastern U.S.

Habitat: Lakes, rivers, ponds and ditches. Common: most Washington waters. Nuttall's: fresh to slightly brackish water.

May be confused with: Brazilian elodea (Egeria densa), which has a similar appearance, but has longer leaves in whorls of 4 to 6. Hydrilla (Hydrilla verticillata) which has tubers and spiny leaf edges. Coontail (Ceratophyllum), which has forked, needle-like leaves. Also easily confused with each other. Flower structure and leaf width are the most reliable distinguishing characteristics.

Photographs: Elodea canadensis , Elodea nuttallii

Line Drawings: Elodea canadensis