The recent advances in defining genes involved in shoot epidermal cell differentiation are impressive, especially the characterisation of genes involved in cellular patterning. The additional influences of environment and hormones on cellular patterning have recently been emphasised, and important connections have been made to changes in vegetative and reproductive growth phases. Despite these advances the cellular basis for differentiation remains less well defined, but now genetic and cell biological analysis from yeast may provide important models on which to develop further understanding.