XVI International Botanical Congess

The adaxial epidermal cells of many petals have a conical shape. It has been suggested that this shape focuses light within the cells, increasing the amount of light absorbed by floral pigments and enhancing the attractiveness of the petals to pollinators. It has also been suggested that conical cells aid pollinator orientation on the flower, either visually or when touched. The identification of a mutant at the MIXTA locus of Antirrhinum majus (which blocks the formation of conical cells) has allowed us to test these hypotheses. Field experiments indicate that flowers with conical epidermal cells set more fruit than those with flat cells. Studies of bee behaviour indicate that conical cells increase the number of bees both landing on and probing flowers, suggesting that these cells play visual and tactile roles in enhancing pollination success.