Two papers describe a novel Arabidopsis gene with a crucial role in the differentiation, shape and form of petals and leaves. On p. 1101 and p. 1111, both Dinneny et al. and Ohno et al. have characterised JAGGED (JAG), the loss of which causes the distal regions of petals and leaves to become misshaped. JAG expression in organ primordia coincides with regions undergoing active cell division, and in JAG mutants, cell-cycle activity declines abnormally early. The authors suggest that JAG slows down the cessation of cell division in distal regions of the organ primordia until proper morphogenesis occurs, thereby suppressing premature differentiation. Curiously, although JAG is not necessary for the initiation of organ formation, its ectopic expression can induce tissue proliferation. Most strikingly, JAG misexpression causes the formation of bracts - elongate leaf-like organs located just below flowers - which are not normally produced by Arabidopsis. Both groups speculate that the exclusion of JAG from the bract-forming region may be the cause of bractless flowers in Arabidopsis and other Brassicaceae.