Elodea

Scientific name

Elodea Michaux

Common names

pondweed, oxygenweed, yankeeweed

Family

Hydrocharitaceae

Native distribution

America

Species commonly cultivated

Elodea canadensis Michx. (North America)

E. nuttallii (Planchon) St. John (North America)

Adventive distribution

Elodea canadensis is widely distributed on most continents, while E. nuttallii is established in Europe and Asia.

Weed status

Elodea canadensis is a serious weed in more than 45 countries around the world, where it obstructs waterways and irrigation. This species is prohibited in several countries, including Australia and New Zealand.

Habit

obligate submersed, attached stem plant

Brief description

Annual or perennial. Stems elongate, some ascending and others stoloniferous and close to substrate, unbranched adventitious roots produced from basal nodes. Leaves in whorls of 3-8, regularly spaced along stem, condensed near apex, sessile; leaf blade linear to obovate; margin entire with fine serrations. Inflorescence axillary; spathe of two united bracts. Flowers unisexual; male flowers solitary, floating on water surface, attached to long threadlike pedicel or abscising; female flowers solitary, subsessile but appearing long-pedicellate, opening at water surface; sepals 3; petals 3 (rudimentary or absent in male flowers). Dispersal by seeds, stem fragments or resting turions.

Natural habitat

still waters of lakes, streams, and rivers, especially artificial impoundments

Additional comments

Elodea contains five species native to America. Elodea potamogeton (Bertero) Espinosa and E. callitrichoides (Rich.) Caspary are endemic to South America, while E. bifoliata St. John is endemic to North America.