Thought to be the largest flower in the world, the Rafflesia tuan-mudae is actual a parasitic fungi plant that can only attach itself to one type of Rainforest vine.
Taking 18 months to grow to the size of a red brown cabbage, it them flowers for just 3 days, giving opportunity for flies and other insects to cross-pollinate the male and female pollen, and then land on another target vine. This means that the reproduction process is very very very unreliable.