The world's largest flower grows in the rainforests of Southeast Asia. But its enormous, bright red bloom does not fill the air with a sweet aroma. In fact, the Rafflesia arnoldii is known as the "corpse flower" because it smells like dead flesh. And unlike most plants, this flower does not use energy from the Sun to make its own food. Instead, it is a parasite: it gets all its nutrients and water from a host, a vine in the grape family.