The white blanket muffles distant sounds. Serenity embraces me. This new 19 inches of snow creates a winter wonderland that I love to be a part of.
Eastern hemlock, white pine, mountain laurel and rhododendron sporting dollops of snow on evergreen leaves make for a white, green and brown landscape. But wait, there’s splashes of orange here. Not all deciduous trees stand stark naked. There are misfits about. Orange leaves still cling to branches of young beech. What’s with this?
I crumple a handful of lifeless American Beech (Fagus grandifolia) leaves, but they don’t crumble into pieces. They are dry, yet springy. This is one reason why resourceful early settlers collected these leaves and stuffed their mattresses with them. I can see how they would be so much better than straw that would compress.
This retaining of dead leaves or other plant parts, is called marcescence. I’ve found it on oaks (Quercus) and witch hazel (Hamamelis) too. Why would a tree hang onto its leaves all through the winter? A couple theories are bantered about.
It’s primarily the young trees that clutch determinedly to their dead photosynthetic factories. They are the ones whose branches are within reach of browsing deer and moose. These large herbivores are seeking succulent buds and twigs for nourishment in the winter. The dry parchment-like, leaves perhaps act as unpalatable deterrents and help the young trees retain their branches.
Perhaps too, water retention or temperature control may play a part. Evolutionarily speaking, perhaps the beech and oaks have not yet mastered being deciduous yet. Maybe these youngsters retain some fragment of a time when losing leaves for the dry part of the year had not yet become a necessity, and it is advantageous for them to retain leaves when young.
Fact is, nobody really knows the reason for marcescence. We do know how it occurs. The abscission layer, separating a leaf and its twig, is formed in autumn. This shuts the leaf off from its supplies, causing it to drop. The abscission layer is not fully formed with marcescent leaves. Why, isn’t known. I just know it is nice to have a mystery afoot to keep curiosity alive on a winter hike through the woods.
Copyright © 2009. NaturePods. All Rights Reserved.