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.

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.

It would seem that this evolutionary development would make the trees more vulnerable to branches breaking off under snow and ice load in the winter. That seems to be counterproductive. Any thoughts on how this might also be beneficial to the tree, outweighing the potential damage? Thanks

Hi Mark:

Great follow-up question! Based on some some urban forestry ice storm susceptibility research, oaks (Quercus) rank from susceptible (black oak; Q. velutina), to intermediate (n. red oak, chestnut oak, pin oak), to resistant (bur oak; Q. macrocarpa & white oak; Q. alba). American beech (Fagus grandifolia) ranks as intermediate in ice storm susceptibility. Therefore, these species have adaptations [branch strength/elasticity; branch angles; crown form (excurrent vs. decurrent); crown canopy position; etc.]

Rather than copy and paste from a great publication, please conduct a simple internet search for the following publication:

Trees and Ice Storms: The Development of Ice Storm-Resistant Urban Tree Populations, 2nd Edition

Best, Jay C. Hayek

I have noticed young Red Oaks in the Dallas Tx area also retain many of their leaves until spring. Thank you for posting an explanation for this behavior.

Jay,

It there specific species/genus types for the kinds of oak that are marcescent? Or do they randomly occur in all species of oak?

This was not helpful. We asked WHICH OAK SPECIES retain their brown leaves until the next spring. You didn't answer that. Your explanations of why they do it and how they adapt to ice storm damage by having heavier limbs etc is interesting but doesn't tell me which oak species I have here in my yard with brown leaves all still stuck on it in February. Ray

In our area, Burr Oaks hold their leaves until spring when the new growth “pushes” the old leaves off.

I have a chestnut oak that keep’s leaves all winter.

Chestnut oak is definitely a species that tends to retain its leaves well throughout winter as well.