By January, most deciduous trees have completely shed their leaves. Two major exceptions to this rule are oaks and beeches. If you look outside and see a tree still clinging to masses of dried, curled up brown leaves, chances are you have one of these trees. 

To help you pick out the eastern white oaks (Quercus alba) from the rest, look for the following characteristics: 

• Light grey to nearly white bark, broken into numerous chip-like scales, sometimes with a pink tinge (Does anyone know what causes the pink coloration? A fungus or lichen perhaps?)
• Blunt egg-shaped winter buds with numerous chestnut-brown scales clustered at the ends of twigs 
• Leaves with rounded rather than pointed lobes, generally 5 to 9 inches long and 2 to 4 inches wide, although foliage can be highly variable, even on the same tree). 

But why would eastern white oaks retain their dead leaves through the winter? Although the “why” is still somewhat uncertain, this phenomenon of the retention of dead plant matter is called “marcescence”. Although any oak could exhibit this condition, it is most commonly observed on young trees and on lower branches of more mature trees. The leaves do not fall because they do not develop complete abscission layers in the leaf stems that would cause them to drop off. Some researchers suggest marcescence is more common in areas of dry, infertile soil, and that by not dropping their leaves until the spring the oaks can deliver organic material to the forest floor at a time when it is most needed by the growing parent tree. Others have posed that persistent leaves could provide some frost protection for buds and new twigs over winter.