How did the variety of leaf forms evolve?

Leaves come in many shapes and sizes, from simple flat blades to elaborate vessel or pitcher shapes found on some carnivorous plants. How do plants create this diversity of forms? You might think they do it much as a potter creates different shapes with clay. But unlike pottery, there is no external hand guiding the process of plant growth. Leaves have to construct themselves. Each leaf starts from a small group of cells in a bud, a fraction of a millimetre across. The bud turns itself into a leaf through internal rules of growth. We would like to define these rules and understand how they lead to the growth of diverse leaf shapes, from the simplest to the most complex. The vessel shaped leaves of carnivorous plants are particularly intriguing as this leaf form has evolved four times independently in carnivorous species, as an adaptation to trapping animal prey.

The four independent origins of vessel-shaped leaves are: Bladderwort suction traps plant (Utricularia), Albany pitcher plant (Cephalotus), tropical pitcher plant (Nepenthes) and American pitcher plants (Sarracenia). The movie shows a journey through an example from each of these groups, imaged using Optical Projection Tomography.

Please click on the images below to find out about each animal eating leaf shown in the movie.