ABSTRACT
The shoot meristem is initiated and develops within an embryo during the process of embryogenesis that occurs from a zygote. The initial shoot meristem becomes the shoot apical meristem (SAM) during later developmental stages because of its position at the growing tip of the plant. Except for the root, all lateral organs in a plant derive from the flanks of the SAM. As a result of histological analyses, the SAM is subdivided into three distinct zones, the peripheral, central, and rib zones (Figure 13.1). Lateral organs are derived from the peripheral zone, stem tissue from the rib zone. The central zone acts as a type of stem cell resource, which replenishes both the peripheral and rib zones while maintaining itself as the source of stem cells.
