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What roles do nodes and internodes play in the growth of a tree stem?

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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.

In the growth of a tree stem, nodes and internodes are fundamental structural components that facilitate development and height increase.

Nodes: These are the specific points on a stem where leaves, buds, and lateral shoots (branches) originate. The positional relationship between the stem, leaf, and axillary bud at the node is essential for understanding the diversity of a tree's shoot system.12
Internodes: These are the regions or intervals located between successive nodes.12

The primary height growth of a tree is determined by the number of "height growth units"—defined as a node plus its subtending internode—produced during a growing season, combined with the elongation of those internodes.3

The growth process is highly dynamic:
* Elongation: The lengthening of internodes is a key factor in how a tree increases in height. Variations in internode length can lead to vastly different plant forms; for instance, extreme shortening results in rosette patterns, while extreme lengthening can produce vining habits.31
* Regulation: This growth is sensitive to environmental factors and hormonal influences, which dictate when these units are initiated and how much they elongate. During periods of dormancy, internodal elongation ceases, even if other biological activities continue within the buds.3