Pistia stratiotes aka Water Lettuce

Pistia stratiotes, also known as water cabbage, water lettuce, Nile cabbage, or shellflower, is the sole species in the genus Pistia and the tribe Pistieae in the arum family, Araceae. Its native distribution is uncertain but is believed to be pantropical, and it was first discovered in the Nile near Lake Victoria in Africa. It can now be found in almost all tropical and subtropical fresh waterways, either through natural means or human introduction, and is considered an invasive species and a mosquito breeding habitat. The genus name comes from the Greek word "pistos," meaning "water," referring to the aquatic nature of the plants, while the specific epithet is derived from the Greek word "stratiotes," meaning "soldier," in reference to the sword-shaped leaves of some plants in the Stratiotes genus. Pistia stratiotes has the potential to reduce the biodiversity of waterways and can be a weed due to its growth habit. The mats of water lettuce can block gas exchange at the air-water interface, reducing oxygen in the water and killing fish, as well as blocking light and killing native submerged plants. It is toxic if eaten in large quantities and can be invasive in locations with year-round warm temperatures and high humidity. However, the roots of Pistia stratiotes serve as a shelter for fish, and it grows in still waters of ponds, ditches, swamps, and slow-moving streams.