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The largest single flower belongs to Rafflesia arnoldii, or the 'Corpse flower'.

It is a parasitic plant, with no visible leaves, roots, or stem. It attaches itself to a host plant to obtain water and nutrients. When in bloom, the Rafflesia emits a repulsive odor, similar to that of rotting meat. This odor attracts insects that pollinate the plant.

Rafflesia arnoldii is a member of the genus Rafflesia. It is noted for producing the largest individual flower on earth. It occurs only in the rainforests of Sumatra and Borneo in the Malay Archipelago.

Recent molecular taxonomy studies have resulted in assigning Rafflesia arnoldii to the family of Euphorbiaceae.

The Titan Arum (Amorphophallus titanum) and Talipot palm (Corypha umbraculifera) appear to have bigger flowers, but they are technically clusters of many flowers.

The world's largest sunflower stands at 32.5" wide whereas the average Rafflesia can have a flower as large as 39" wide.
The Rafflesia arnoldii.The flower with the world's largest bloom is the Rafflesia arnoldii. This rare flower is found in the rainforests of Indonesia. It can grow to be 3 feet across and weigh up to 15 pounds! It is a parasitic plant, with no visible leaves, roots, or stem. It attaches itself to a host plant to obtain water and nutrients. When in bloom, the Rafflesia emits a repulsive odor, similar to that of rotting meat. This odor attracts insects that pollinate the plant