AMORPHOPHALLUS TITANUM
The Titan Arum, from the Araceae Family, at the Singapore Botanic Gardens is flowering and just as I am typing this, the inflorescence has probably reached its peak in flowering and the flesh-rotting smell is unleashed. Unfortunately or fortunately, I am not there to see the army of beetles and flies seeking out the flowers.
The Rafflesia that I posted earlier has the world's largest single flower, but this aroid has the world's largest unbranched inflorescence. The bracts wrapping the inflorescence look like a yummy vegetable and would unfurl itself. A link on the plant is shown below: