Meristematic cells in plants become the many different types of cells found in a mature plant. This is achieved by a selective response to chemical signals both from neighbouring cells and distant tissues. It is these responses that shape the plant, its time of flowering, the sex of its flowers, its length of survival or progress to senescence and death. How do plants achieve this? This treatise addresses this question using well-chosen examples to illustrate the concept of target cells. The authors discuss how each cell has the ability to discriminate between different chemical signals, determining which it will respond to and which it will ignore. The regulation of gene expression through signal perception and signal transduction is at the core of this selectivity and the Target Cell concept. This volume will serve as a valuable reference for all researchers working in the field of plant developmental biology.