Appearance

Sparganium erectum is a perennial wetland or aquatic herbaceous plant that is native to North America. It grows from slender rhizomes with slender terete stems. S. erectum grows from 3-8 ft. (0.9-2.4 m) tall. It is found around the world and is listed as native to North America, Africa, temperate Asia and Europe.

Foliage

The long flat leaves are alternate. They are often slightly keeled. The leaves may be either floating or held above the water.

Flowers

The inflorescence is branched. Each inflorescence has from 5-13 staminate heads and 2-4 pistillate heads. Pistillate heads are sessile.

Fruit

Fruits are obovoid sessile nutlets. Fruits have a truncated top with a small style at the tip.

Ecological Threat

Sparganium erectumis a federally listed noxious weed. It can be found in California and other states, as well as Canada. S. erectum is listed as introduced to Australia.

Resources

• Federal Noxious Weed Disseminules of the U.S. - USDA-APHIS

Selected Images

Maps

Invasive Listing Sources

• Federal Noxious Weeds
• Florida Noxious Weeds
• Indiana Invasive Species Council - Invasive Plant List
• Indiana Prohibited Plant Species
• Massachusetts Noxious Weeds
• Massachusetts Prohibited Plant List
• Nonnative Invasive Species in Southern Forest and Grassland Ecosystems
• South Carolina Illegal Aquatic Plants
• South Carolina Plant Pest List
• USDA APHIS Regulated Pest List

References