Which species is known as the world’s largest single flower?

Rafflesia arnoldii is widely known as the world’s largest single flower.

This species produces enormous reddish-brown flowers that can exceed one metre in diameter. It is native to parts of Sumatra and Borneo and lives as a parasite inside vines of the genus Tetrastigma. Most of the plant remains hidden within its host; the conspicuous flower is its most visible structure.

The flower emits a powerful smell resembling rotting meat. That odor attracts carrion flies, which act as pollinators. Rafflesia arnoldii has no ordinary leaves, stems, or roots, making it radically different from familiar flowering plants.

A common mix-up is Titan arum, or Amorphophallus titanum. Titan arum produces the world’s largest unbranched inflorescence, meaning a cluster of many tiny flowers, whereas Rafflesia produces one giant flower. The distinction explains why both plants are described with superlatives.