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How do shoot apical meristems produce new leaves and branches?

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Tall giant sequoia trees with reddish bark and thick trunks rise closely together in a dense forest at Sequoia National Park, California. — Tree A stand of giant sequoia trees (*Sequoiadendron giganteum*) in Sequoia National Park, California.

Shoot apical meristems are regions of active cell division located at the tips of stems and branches, serving as the primary centers for plant growth and development. They produce new leaves and branches through the following processes:1

Production of Leaves

Leaves originate on the flanks of the shoot apex. The process begins with a local concentration of cell divisions that forms a small, nipple-shaped structure known as a leaf buttress. As this primordium grows, meristematic activity—often involving marginal meristems—allows the leaf to extend and develop its specific shape, such as the laminate form seen in many dicotyledons. The vascular system of the leaf is initiated early through the formation of procambial strands that eventually link with the stem's vascular tissue.2

Production of Branches

Branches arise from axillary buds, which are initiated on the flanks of the main shoot apex, typically in the angle between a leaf and the stem (the leaf axil). These lateral shoot apices begin as miniature versions of the main apex. Once a lateral apex reaches a minimal volume, it begins to organize its own primordia and grow into a new shoot.3

The development of these branches is often regulated by apical dominance, a phenomenon where the main terminal bud inhibits the growth of lateral buds through the flow of hormones like auxin. If the terminal bud is removed, this inhibition is lifted, allowing the lateral buds to resume growth.43