Subtle origin for complex shapes The cup-shaped leaves of carnivorous plants have evolved multiple times from ancestors with flat leaves. Studying development of the carnivorous trap in the humped bladderwort, Utricularia gibba , Whitewoods et al. identified genes similar to those expressed in surfaces of flat leaves (see the Perspective by Moulton and Goriely). Ectopic expression and computational modeling reveals how slight shifts in gene expression domains make the difference between a flat leaf and a convoluted trap structure. Flexibility in growth rates in orthogonal polarity fields allows for diversity in shapes formed through development. Science , this issue p. 91 ; see also p. 24