Water lettuce Information & Care
|Back to Freshwater Aquarium Plants Species|
|Plant Type||Floating plant|
|Common Name||Water lettuce|
Pistia is a genus of aquatic plant, its members are often called water lettuces. Its native distribution in uncertain, it can survive in all temperate fresh waterways.
Pistia floats on the surface of the water its roots roots hanging submersed beneath floating leaves. It is a perennial monocotyledon with thick, soft leaves that form a rosette. The leaves can be up to 14 cm long and have no stem, they are light green, with parallel veins, wavy margins and are covered in short hairs. The flowers are dioecious, and are hidden in middle of the plant amongst the leaves, small green berries form after successful fertilization. The plant can also undergo asexual reproduction, mother and daughter plants are connected by a short stolon, forming dense mats.
The growth habit Pistia can make it a weed in waterways, Pistia stratiotes is a common aquatic weed in the United States, particularly in Florida where it may clog waterways. Pistia has the potential to reduce the biodiversity of a waterway. Mats of Pistia block gas exchange at the air-water interface, this reduces the oxygen in the water, killing fish, they also block light killing native submerged plants, and alter emersed plant communities by crushing them.
Pistia can be controlled by mechanical harvestors that remove the water lettuce from the water and transport it to disposal on shore. Aquatic herbicides may also be used. Two insects are also being used as a biological control. Adults and lavae of the South American weevil, Neohydronomous affinis feed on Pistia leaves, and the lavae of moth Spodoptera pectinicornis from Thailand, both are proving to be useful tools in the management of Pistia.