Crown (botany)

Tree crown

The crown of a plant refers to the totality of an individual plant's aboveground parts, including stems, leaves, and reproductive structures. A plant community canopy consists of one or more plant crowns growing in a given area.

The crown of a woody plant (tree, shrub, liana) is the branches, leaves, and reproductive structures extending from the trunk or main stems.

Shapes of crowns are highly variable. The major types for trees are the excurrent branching habit resulting in conoid shapes and decurrent (deliquescent) branching habit, resulting in round shapes. Crowns are also characterized by their width, depth, surface area, volume, and density. Measurements of crowns are important in quantifying and qualifying plant health, growth stage, and efficiency.

Major functions of the crown include light energy assimilation, carbon dioxide absorption and release of oxygen via photosynthesis, energy release by respiration, and movement of water to the atmosphere by transpiration. These functions are performed by the leaves. Branches of the crown provide mechanical support to distribute the leaves efficiently and serve as conduits for resources (water, nutrients, photosynthates) to perform these functions.

Crown classes

Trees can be described as fitting different crown classes. Commonly used are Kraft's classes: Dominant, Subdominant, Suppressed etc. . Also IUFRO has a some classes for storeys of trees. These may be referred to as A, B, C etc.

See also

• Apical dominance
• Canopy (biology)
• Canopy (grape)
• Diameter at breast height
• Fruit tree forms
• Growth habit (determinate growth, indeterminate growth, semideterminate growth, flushing growth, etc.)
• Habit (biology)
• Pruning
• Understory

References

• Tree crown
• Kozlowski, T.; Kramer, P.; Pallardy, S. (1991) The physiological ecology of woody plants. Academic Press