Water lettuce (Pistia stratiotes) is a free-floating aquatic plant characterized by its light green, velvety, and ribbed leaves that resemble a head of lettuce. It is a rapid grower, forming dense mats that can cover entire water surfaces in tropical and subtropical regions. While beneficial in some ways, it's also considered an invasive species in many areas due to its rapid spread and potential to disrupt ecosystems. 

Pistia stratiotes /water cabbage/ water lettuce (1 plant)

Here's a more detailed description:

Appearance:

Water lettuce has soft, light green leaves arranged in a rosette pattern, giving it a lettuce-like appearance. The leaves are covered in fine hairs, making them feel velvety to the touch. They can grow up to 6 inches wide and 10 inches long, with prominent veins. 

Growth:

It is a free-floating plant that spreads by vegetative reproduction, forming new plants from stolons (runners). 

Habitat:

It thrives in warm, freshwater environments, including ponds, lakes, rivers, and canals. 

Invasive Potential:

Water lettuce can quickly form dense mats that block sunlight, restrict water flow, and displace native aquatic vegetation. It can also interfere with recreational activities like boating and fishing. 

Benefits:

In controlled environments, it can be used to absorb excess nutrients from the water, helping to prevent algae blooms. It also provides cover for small fish and fry in aquariums. 

Distribution:

Native to tropical and subtropical regions, it has become widespread in many parts of the world, including the Americas, Africa, and Asia.