When I posted this photo on Monday to highlight the flowering Hippeastrum, I couldn’t help but look beyond the windows to admire the parchment-like leaves of a group of young American beech trees (Fagus grandifolia), and the warm color they add to the mostly gray and brown winter landscape.
The native beech is common in our neighborhood and easy to spot any time of year because of its smooth gray bark, which is sometimes carved by lovebirds and others who want to make their mark. In fall, the tree’s green leaves turn yellow and then russet brown, but rather than falling, many cling tightly to their branches throughout the cold season, eventually fading to pale parchment and curling into cylinders that rattle against one another in the slightest breeze.
What accounts for the winter dress of the beech tree?
Most deciduous trees shed their leaves by producing an enzyme that creates an abscission layer between the leaf petiole and the tree branch. When the cell walls of this specialized layer disintegrate, the leaf easily detaches in a gust of wind or sprinkle of rain.
Beeches, however, belong to a group of trees that are marcescent [märˈses(ə)nt], meaning they hold on to all or most of their leaves until spring. Like some oaks and hornbeams, beeches either fail to form an abscission layer or delay its development, so leaves stay on the tree long after they become lifeless and dry.
Marcescence is more common on younger trees and on the lower, more juvenile, portions of older trees. In my garden, this is particularly true of oaks, but these dull brown, crinkled leaves are a poor substitute for the beech’s tiers of lacy, warm-hued foliage.
No one really knows the purpose of marcescence, but there are theories. Some believe the unpalatable leaves keep tender buds and branches from being browsed by hungry herbivores like deer and moose. Others suggest the leaves provide protection from injury when conditions are especially dry or frigid.
Whatever the reason, I love the rich color the beech trees add to the winter landscape and the whispered conversations offered by their shimmering leaves when I walk among their branches. Surely they must be chatting about spring, and the many blue skies and warm days just ahead.