Tag Archives: topic:Geometry

Spirals in nature: Phyllotaxis

Mathematics: Christophe Gole (Smith College)
Biological Sciences: Denise Lello ( Smith College)

The majority of plants display Fibonacci phyllotaxis, featuring Fibonacci numbers of spirals in the arrangement of their organs. We study a dynamical model that offers an explanation of why Fibonacci phyllotaxis is so predominant. It also explains a recently discovered type of pattern (Quasi-symmetry), where the number of spirals does not follow a Fibonacci like progression, but come in pairs of numbers that are close to one another (e.g. 12, 11 or 20, 22). Recent advances in our understanding of the biochemistry of plant pattern formation provide a crucial link between models and natural history. We study the transitions between the different kinds of patterns observed in the models and in nature and their connection to the plant’s vasculature. Students work on growing and dissecting the plants, macro- and microscopic imaging, data gathering, modeling, programming and mathematical analysis. Dynamical systems, geometry, number and group theory are some of the mathematics involved.