Plant morphogenesis: Designing leaves

Leaves exhibit a wide range of form and function: as well as the flattened photosynthetic organs we are most familiar with, modifications of leaf morphology produce the rigid spines of cacti, the cup-shaped insect traps of pitcher plants, colorful flower parts such as petals and some of the tendrils used for attachment by climbing plants. One fundamental choice in leaf architecture is whether to be simple or compound (see Fig. 1a–c). Simple leaves can have simple shapes — such as round, oval or strap-like — or they can be lobed, like an oak leaf. In contrast, compound leaves are subdivided into smaller units called leaflets.