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Why Some Oak Trees Retain Their Leaves

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From: Timothy Skura
City:
Buffalo, NY
Jay, why is it that some oak trees and I think one other type maybe that I have noticed their leaves stay on after fall and into the winter. They turn brown as if they are dead but still hang onto the trees. I live in Buffalo NY and that is how some are around here.

 
Extension Message
From: Jay Hayek
Extension Specialist, Forestry
Department of Natural Resources and Environmental Sciences
jhayek@illinois.edu
Greetings Timothy,

A common site out in the forests of the Midwest is the noticeable retention of dead leaves on certain oaks (Quercus spp.), American beech (Fagus grandifolia), ironwood (Ostrya virginiana), and musclewood (Carpinus caroliniana). The clinging dead leaves are commonly referred to as marcescent leaves. The physiological process responsible for this phenomenon is commonly referred to as marcescence: the retention of dead leaves that otherwise would be shed during autumn. Moreover, the physiological process commonly used to explain this process is the incomplete development of an abscission layer at the base of the leaf’s petiole during autumn: a time when diminished photoperiod and cooler temperatures triggers plant growth inhibitors such as abscisic acid. Thus, the incomplete development of an abscission layer in the leaves of certain species facilitates the retention of dead leaves that otherwise would have fallen naturally. High winds during autumn and winter, including the breaking of dormancy during spring, causes many of these marcescent leaves to eventually fall to the ground. This phenomenon more commonly occurs on juvenile trees; and in the lower crown of more mature trees.

 
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