SafePlants

Swamp Loosestrife (Decodon verticillatus)

Swamp Loosestrife, also known as Waterwillow or Whorled Loosestrife, is an attractive native wetland plant often found in eastern North America.

Considerations for Pets

• Swamp Loosestrife is a shrubby plant.
• It grows in swamps and shallow water, which may present water safety considerations.

Considerations for Children

• Swamp Loosestrife is a shrubby plant.
• It grows in swamps and shallow water, which may present water safety considerations.

Taxonomy and Nomenclature

• Scientific Name: Decodon verticillatus (L.) Elliott
• Common Names: Swamp Loosestrife, Waterwillow, Whorled Loosestrife, Wild Oleander
• Family: Lythraceae (Loosestrife Family)
• Synonym: Nesaea verticillata

Distribution and Habitat

• Native to swamps and ponds of eastern North America.
• Found in swamps, shallow water, marshes, standing water, and riverbanks.
• Grows in wetlands all along the east coast.
• Range includes Wisconsin to other locations, as well as Nova Scotia.
• Rooted onshore or in shallow water with an emergent body.

Ecological Role

• Important to distinguish from the highly invasive purple loosestrife (Lythrum salicaria).

Morphological Characteristics

• Clump-forming shrubby perennial.
• Sprawling, woody herb.
• Forms arching stems about 3-8 feet long that are unbranched or sparingly so.
• Base of each stem is spongy and swollen.
• Flowers are pinkish purple, about 1/2 inch across.
• Whorls of 1-inch flowers with 4 to 7 wrinkled petals and long spidery stamens.

Quirky Facts

• The genus name Decodon comes from the Greek "deca" for ten and "odus" for tooth.
• The species name verticillatus comes from the Greek word meaning "whorled".

Further Information

• UF/IFAS Center for Aquatic and Invasive Plants
• Discover Life
• USDA APHIS PPQ