In his book, Symmetry: A Journey Into the Patterns of Nature, Marcus du Sautoy explains that symmetry is not just aesthetics. Symmetry is a sign of genetic superiority. Symmetry creates balance for speed and agility, it communicates nutrition, and attracts pollinators in the case of flowers. It's not easy. Symmetry is an extravagance. Only the fittest have enough energy to spare to create shapes with balance.
This video, demonstrating the prevalence of the Fibonacci numbers and spirals in plants, is really well done. Created for the middle school audience, it is fun and fast.