While we admire flowers for their aesthetics, their colors, shapes and aroma all have specific functions. They have evolved to be attractive to pollinators which is necessary for the plants' propagation. The iris bloom shown here is a good example. It has evolved a complex shape and color scheme which attracts insect pollinators. The entrance to the flower is separate from the exit. The pollinating insect that lands on this flower first finds stamens on which it deposits some of the pollen it has collected from previous blooms. The pollen stems on the iris are located at the exit and the insect collects them on its way out to other blooms. This sequence ensures the iris is not pollinated with its own pollen.