Technical Abstract: Understanding the developmental morphology of forage plants is important for making good management decisions. Many such decisions involve timing the initiation or termination of a management practice to a particular stage of development in the life cycle of the forage. The life cycles of forage plants are characterized by distinct changes in plant morphology. The ontogeny of most forage plants involves seedling, vegetative, and reproductive stages of development. Interactions among leaf, tiller and root meristems are coordinated to assure the orderly development of the plant. Transitions among growth states occur in a predictable manner and are useful for describing the maturity of individual plants as well as populations or stands. The growth processes of each organ depend on cell division and elongation to provide the ultra-structure for plant tissue development and biomass accumulation. The cell division and elongation zones are sites of high metabolic activity and dry matter accumulation. Elongated cells then differentiate to form specific organs and accommodate associated physiological functions. As cells mature and their photosynthetic apparatus develops they undergo a transition from carbon sink to carbon source for the rest of the leaf. Similarly, as leaf development continues the leaf as a whole ceases to be a sink and becomes a source for younger leaves. This presentation is concerned with the initiation, expansion, and maturation of leaves, stems and roots, and with the transition from vegetative to reproductive growth and production of reproductive tissues, all of which have profound effects on forage yield, quality and stand longevity.