Thumbwort Alisma plantago-aquatica

The European Water Plantain is an aquatic perennial in the water plantain family (Alismataceae).  It is native to northern temperate regions of Europe, Asia, and northern and central Africa.  The plant is found on mud, in lakes, rivers, ditches, ponds, and grazed shores in its native environment.  The genus name is the Celtic word for water.

The plant grows 2-3 feet tall and about 18 inches wide.  The plant prefers full sun and wet, poorly-drained soil.  It will survive in 12-18 inches of water and containers of water.  Self-seeding can be a problem if the flowers are not deadheaded.  Propagation is by rhizome division in spring or seed.

The tiny white to pale pink flowers are very fragrant and bloom late spring and summer in whorls on long stems.  The flowers attract bees and flies.  The fruit is eaten by wildlife.  The foliage may cause skin irritation.  The common name, Mad-Dog Weed, refers to its medicinal use to treat rabies.  There are few commercial nurseries in the United States that sell it. The leaves and roots are edible but must be boiled or dried to destroy its toxic ingredient.

Grow this aquatic plant in marshy areas, ponds, bogs, and wet areas.

Insects, Diseases, and Other Plant Problems:  No serious pest or disease.  The plant can be weedy and spread via self-seeding.  Slugs are attracted to the plant.