Based on examination of wild type pedicels we propose that there are three stages of pedicel development: a proliferative stage, a stomata differentiation stage and a cell elongation stage. Our analysis uncovered coordination of cell behavior within tissues and between different tissues: the onset of stomata differentiation was linked to pavement cell elongation, the termination of asymmetric cell divisions in the epidermis was followed by acceleration of the cell cycle in the cortex, and the termination of stomata differentiation was coincidental with cortex cell elongation. We observed that during the final stage of development pedicel Cinoxacin growth was dependent on flower fertilization, and we propose that some unknown signal coming from the flower promotes cell elongation in the pedicel. Detailed temporal analysis of er revealed that the mutation affects the growth rate during the first two stages of pedicel development. In the cortex and epidermis of the mutant we observed a decreased cell growth rate and increased cell cycle duration but only very subtle changes in the size of cells at division. In er epidermis meristemoid differentiation was premature and prolonged. Interestingly, the prolonged period of asymmetric divisions in the epidermis of the mutant was coincidental with a lack of cell cycle acceleration in the cortex. Our investigation demonstrates that pedicels are a useful model for studying the coordination and interdependence of different tissues during plant organ development. It has been shown previously that silique growth strongly depends on flower fertilization. We investigated whether flower fertilization has an effect on the growth of pedicels. Pedicel growth was analyzed in three situations: when the flower was undisturbed; when sepals, petals and stamens were removed and then the pistil was hand pollinated; and when the above mentioned flower organs were removed and the pistil was not pollinated. Removal of flower organs did not affect pedicel growth. Fertilization was important for the rate of growth but not its duration. After fertilization, growth continued for 4 days in both cases, but pedicels carrying unfertilized flowers grew more slowly and were shorter. Fertilization triggers auxin and 3,4,5-Trimethoxyphenylacetic acid gibberellin biosynthesis in siliques, and the flow of these hormones through the pedicel might be necessary to maintain its high growth rate. Since pedicels develop in close proximity to the inflorescence meristem, we investigated whether the meristem affects their growth by removing the meristem and monitoring the growth of a pedicel attached to the flower at stage 12. The removal of the meristem at that stage did not change the rate of pedicel growth. An organ grows due to growth and division of its cells with both of these processes being coordinated at the tissue levels and between different layers. As in many other plant organs, there are three tissues in pedicels: epidermis, cortex/mesophyll, and vasculature. Here we describe the behavior of cells in the epidermis and cortex and ignore for now the vasculature. We use the term ��cell proliferation’ to refer to cells that grow and then divide, and the term ��cell expansion’ to refer to cell growth that is not associated with cell divisions. To understand mechanisms controlling size and shape of plant organs it is essential to know the contributions of cell proliferation and cell elongation, and how growth is coordinated between different tissue layers. Here we examined pedicel development with the goal to learn more about the cellular basis of growth and pattern formation in plant organs. As a result of our analyses of epidermis and cortex, we propose that there are three stages of pedicel development. The switch to cell elongation requires a transition from the mitotic cell cycle to endoreduplication in epidermal cells.