In the improvement and management of crops in which fruit and seed comprise economic yield, particular attention must be paid to the timing and extent of reproductive development. Successful cultivars are able to complete reproduction within available growing seasons, avoid stresses at vulnerable stages and, for maximum yield, balance available time and resources between vegetative and reproductive growth.

Anatomical and physiological bases of organ formation are important background for crop ecology, requiring integration of information from genetics, plant physiology, morphology, and development. Apical meristems of shoot and root have the capacity for unlimited growth and produce the elongating body of the plant. Shoot meristems progress with periodic production of new leaves at stem nodes separated from each other by internodes. Intercalary meristems in internodes also contribute to shoot elongation while new apices in leaf axils (axillary meristems) provide branching. Lateral meristems, mainly vascular cambia, increase girth. Meristems convert from production of leaves to flowers in a direct response to environmental signals of temperature and daylength, indirectly to environment through assimilate supply, and in some cases with age.

This chapter deals with coordination and timing of initiation, growth, and longevity of vegetative and reproductive parts, and also with seed germination. It provides the necessary background to cultivar improvement (Chapter 4) and crop management (Chapters 13, 14, 16, and 17).