Yellow Sawah Lettuce or Yellow Burr Head plant is a Exotic plant to Sri Lanka now naturalized from it's native countries that Mexico and South America. It is a invasive aquatic weed that plant encourages spread to marsh land like border of paddy field, or water streams and commonly found in Wet Zone and Dry zone in the country. The plant is edible and use as a vegetable in some countries but  rarely  use in Sri Lanka as a vegetable or herbal.