7. Titan Arum in Olbrich Botanical Gardens, Madison, Wisconsin (U.S.)
Being one of the largest flower in the world, the Titan Arum is a rare flower that blooms only 4 to 5 times during its 40 year life. The flower can reach 3 meters in height and it usually releases a very strong unpleasant smell of rot. The Olbrich Botanical Gardens feature such a flower which bloomed in October 2009. If you are in the area and curious about how this flower looks like (and smells), be sure to visit the gardens in the next bloom.