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.