These leaves died before the plant got rid of them. Most deciduous plants use a process called abcision to weaken the base of the leaf and drop their leaves while they are still alive. If the leaf dies first, then they remain attached. These attached, dead leaves are called marcescent leaves.

Sometimes the marcescent leaves are killed by an early frost or by disease, but some plants, such as beech trees and certain oaks, normally keep their dead leaves. It is thought that the dead leaves help discourage deer and other animals from eating the twigs and buds. In the spring, the tree finally drops the dead leaves as it grows new leaves.