The epidermis of an expanding dicot leaf is a mosaic of cells differing in identity, size and differentiation stage. Elsner et al. study leaves of Arabidopsis thaliana wild-type and triple cyclinD3 mutants and find that relative growth rates of individual epidermal cells or small cell groups differ several fold from those of adjacent cells, and change in time. Growth within an individual cell is also heterogeneous, and this spatial and temporal variation is not related to the size of either the cell or the nucleus. The results support the hypothesis that growth heterogeneity of leaf epidermis is not dependent on cell cycle regulation per se.
