Amorphophallus paeoniifolius at XTBG. (Image by LIU Guangyu) 

Amorphophallus paeoniifolius is perhaps one of the ugliest flowers (inflorescence) in the world and to accompany it, it has one of the worst scents that you can imagine. It's hard to get close to the flower when it's releasing its perfume. Fortunately, the foul odor only lasts for a few hours after the flower opens. The plant only blooms when mature and even so it doesn't bloom every year. Flowers last only about 5 days. Even more interesting, during this phase the plant generates heat which can be felt if you have the guts to stick your hand inside the inflorescence. The heat and the smell mimics an animal that has recently died to attract the flies that will pollinate the flower.