The Rafflesia is the largest flower in the world and smells like rotting flesh.
Why it is true
Rafflesia arnoldii can measure more than a metre across and weigh up to 11 kilograms. The flower releases a strong smell of rotting meat to attract pollinating insects such as flies. It has no leaves or visible stem.
Source: Kew Gardens
Would you rather be asked first?
This is the reading side of the site, so the answer is in the sentence above — that is the whole point of it. Test yourself works the other way round: the question comes on its own, and the fact and the explanation only appear once you have answered.