http://www.ted.com/talks/jonathan_drori_the_beautiful_tricks_of_flowers.html

There are a fourth a million speiceis of flowers and just as much variation in pollen. These plants have to find a way to spread their pollen because that is how they reproduce. Some pollen is trasported by wind but that is not the smart way to do it. Most plant trick insects to carrying it. Flowers have adapted to look like insects, look like other plants, be certain colors, and certain temperatures.