Extension Forestry

Tree Form

The final form of a mature tree is determined by the dominant growth of some buds and shoots at the expense of others, a phenomenon known as apical dominance. In pines and most conifers, the trunk or main stem grows more each year than the other branches, and the branches attached to the trunk grow more than the secondary branches. Strong apical dominance in these species results in a very orderly growth habit that forms a conical tree; this type of growth habit referred to as excurrent growth.

Most deciduous trees do not show strong apical dominance and therefore typically exhibit less orderly growth. Instead, many shoots grow at the same rate, many branches form, and it sometimes becomes difficult to identify the main stem. These species are referred to as decurrent or deliquescent growers, and usually have large spreading crowns.

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ISU Forestry Extension - ISU Extension

Contact: Paul Wray
Last Update: January 3, 1997