The largest flower in the world is

Rafflesia arnoldii produces the world's largest individual flower, which can grow up to 1 meter (3 feet) in diameter and weigh up to 11 kilograms. It's a parasitic plant native to Southeast Asian rainforests, particularly Borneo and Sumatra. The other options are much smaller - Nelumbo is a water lily, Hibiscus is a common flowering shrub, and cactus flowers are modest in size.