Math in the Garden
By: Susan Littlefield
We all know plants are amazing organisms, but did you know that some of them have done their math homework as well? Remember back in the dim reaches of high school math class learning about Fibonacci numbers, where each number the sequence is equal to the sum of the previous two? It turns out that many plants with spiraling shapes, such as cauliflower, artichokes, and sunflowers, make use of the Fibonacci sequence to pack their florets as tightly as possible, thereby maximizing the their ability to gather sunlight for photosynthesis. How does a plant accomplish this feat? It uses the hormone auxin to direct the growth of the florets in this most efficient spiral pattern. The way auxin and certain proteins interact within a sunflower, for example, gives rise to the astounding pattern of disk florets -- and later seeds -- in the center of the sunflower. In a recent study, researchers using a mathematical model to predict where auxin would accumulate in a sunflower were able to reproduce exactly the real Fibonacci spirals in sunflowers.