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's health, growth stage and efficiency.
The upper branches of the crown constitute the canopy.
The major functions of the crown are light energy assimilation via photosynthesis, energy release by respiration, and transpiration (loss of water into the atmosphere). All these functions are performed by leaves. Branches of the crown provide distribution of the leaves to perform the above functions efficiently.
