Provides the primary growth of the stems Is the site of lateral organ initiation Exogenous origin of organs In contrast to the root apical meristem, the shoot apical meristem not only provides the primary growth of stems, but it is also responsible for the initiation of lateral organs, such as leaves, axillary buds and some flower parts as well for the branching of the above ground part of the plant. This external initiation of organs is termed an exogenous origin. This median longitudinal section of waterweed (Elodea canadensis, also often named Anacharis canadensis, an aquatic monocot plant) shoot apex, shows numerous leaf primordia developing in a basipetal (i.e. in a downwards direction) manner. The sessile leaf primordia alternate with their stipules (small leaf-like appendages). The shoot apical meristem is located above the youngest leaf primordium (seen as a dark protrusion on the apex) and appears as the narrow and fairly long cone (growth cone). In essence, the entire region shown here represents a growing bud. |
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