Water lilies are aquatic plants known for their large, floating leaves and beautiful flowers that bloom on the water's surface. In the context of Impressionism and Post-Impressionism, they represent a significant subject matter, capturing the fleeting effects of light and color on water, as well as an exploration of nature's beauty. These plants are often associated with the works of Claude Monet, who used them to convey a sense of tranquility and harmony with nature, embodying the core principles of these artistic movements.