Maths in the Botanical Garden. What do we mean when we talk about plants geometry?

Our poster will present an interactive exhibition, we have developed for the Bergamo Botanical Garden “L. Rota”. This project offers a different point of view on the observation of plants and shows some mathematical aspects related to them. To point out geometry in plants, we developed a purple label about "maths" with information about the flower symmetry, the phyllotaxis and the floral formula. We chose a sample of 25 plants as the subject for this educational activity. Each tag contains some images, a geometric design and some concise information. Visitors learn about flower symmetry, that is given by the presence of one or more planes of symmetry. They can discover about phyllotaxis, word from the Ancient Greek phýllon = leaf and táxis = order, used to describe the arrangement of leaves on the plant stem. Finally, they can find out the floral formula, that is, a set of letters, numbers and symbols, which is used by botanists to give a short description of flowers. The educational exhibition has been developed for generic public, from the age of nine up. We have also organised special educational events with primary schools and classes of low secondary schools. Idea and design developed by Centro matematita- Università degli Studi di Milano.