Common Waterweed

 

Scientific Name: Elodea canadensis Michx.
Family: Hydrocharitaceae

 

MORPHOLOGY

 

Habit and Size: Perennial herbaceous plant, 15-60 cm tall.

 

Stem: Fully leafy submerged stem.

 

Leaves: Ovate leaves, 5-10 mm long, curved with whorled arrangement (2-4).

 

Flowers: Dioecious plant with solitary white flowers. Male flowers are sessile with a spathe, but are not present in Italy. Female flowers are white, have six tepals and a few centimeters long capillary peduncle, measuring 4-5 mm. Blooms from May to July.

 

Fruits and Seeds: In Italy, it reproduces only vegetatively, as the male plant has never arrived.

 

DISTRIBUTION AND HABITAT

 

An allochthonous species of American origin, widespread throughout Italy except for the major islands, Calabria, Puglia, and Marche. It grows in calm, shallow flowing water, from 0 to 600 m in altitude.

 

USE

Used in decorative ponds to oxygenate water and provide shelter for small fish.

 

INTERESTING FACTS

 

The plant is fully submerged, but its small white flowers float on top of long peduncles. Since only the female plant has arrived, the flowers are sterile. Considered invasive, but it is in regression due to the decrease in suitable water bodies.

 

Photo: Under a free license by Saxifraga, Jasenka Topic, Peter Meininger.