Wednesday, December 9, 2015

Marcescence and the Legend of the Evergreens

An American Beech tree holding onto its leaves through most of the winter

     While many people know the difference between deciduous trees who lose their leaves during a short time in the Fall, and the evergreen plants who stay green all winter long, few have heard about marecensce. To be honest, while I knew about the phenomenon of how certain species of trees held onto their dead leaves well into winter, I did not know it had a term until just last week. I was attending the graduation of a master naturalist class and marecensce was the topic of one graduates' presentation. That's one of the neat things about being a naturalist, you learn something new all the time.

An Ironwood (Musclewood) with dried marcescent leaves hanging on into winter

     Leaves are shed because deciduous trees are trying to conserve water that may be hard to get once it freezes during winter. Since the shorter days of winter are not conducive for effective photosynthesis anyways, the leaves are no longer needed. So the chlorophyll is no longer produced and we get to see the hidden Fall colors that often had been masked by the green chlorophyll.  An abscission layer, sometimes called a separation zone, is formed between the tree's petiole and leaf that effectively cuts off the leaf and allows it to fall off.

A Pin Oak has had the top part of its leaves blown off but retains the lower ones.

     But some trees, in particular the oaks, beech, hornbeams, and musclewood trees, do not form this layer and the leaves do not just fall off. In fact, some may be retained well into the winter or into early spring, where new growing leaves can finally cause them to drop. Strong winds might still blow off the dead leaves, particular those at the top of the tree first, but otherwise they stay connected. Some also suspect that smaller trees and lower branches may have more marecescent leaves to allow them to get sunlight for a while longer since the higher leaves have fallen off first. Marcescense  is the term given to the retention of dead plant material that is normally shed in other trees.

Ironwood (Musclewood) leaves in winter still hanging onto the branch.

     Why some trees retain their dead leaves and others don't is not completely understood. Some theorize that it may help with predation so hungry herbivores (such as deer) chew on the hanging dead leaves while hopefully leaving the buds and twigs alone, but no one is really sure. Regardless, it is easy to notice these trees these days prior to the strong winds of winter. While I say no one is sure as to why this retention of leaves may have evolved, there is a legend told by the Seneca people, the westernmost nation of the Haudenosanee people (whom some people call the Iroquois) which explains why this came to be.
     I've told this tale many times, though I take some liberties to replace some of the trees they mention that are found in their New York home with some more appropriate to our area. So I substitute the Tamarack (Larch) tree they have with Bald Cypress for example. My version of the story goes like this:
     A long time ago, the continuous struggles of the spirits of winter versus the spirits of summer were taking place and certain beings were choosing sides. While many of the trees tried to stay neutral and just submitted their colors and leaves until the summer spirits won out, a few were determined to show resistance and decided to back the summer spirits. The Conifer Tribe was among these and decided to hold a meeting to decide how to best show their support and resistance.
     So all the members of the tribe gathered, with White Pine taking the lead and telling them of a magic elixir it had brewed that would allow them to stay green all winter long and thus declare their support for the spirits of summer. The American Beech heard about this and asked to take part in the protest. But Bald Cypress took offense at this. He pointed out that Beech was not a member of his Conifer Tribe and should not be allowed to participate.
     While White Pine acknowledged that this was the case, he insisted that the pines and other conifers needed allies, and that if the oaks, beeches, and musclewoods wanted to show their support, they should be allowed to do so. This so upset Bald Cypress that it stormed out of the council, refusing to take part in any more of the activities of the tribe.
     When time came to give each tribal member a dose of the magical evergreen elixir, the Conifers decided to hold one dose for Bald Cypress in case he returned, but he never did. As it was, there was not enough to share with the beeches, oaks, hornbeams, and musclewoods, so they did not get any.  
     When the spirits of winter saw this show of resistance and protest, they howled and caused it to be the coldest, snowiest season in memory. The bitter winds blew and the harsh cold attacked the trees with fury. Most of the trees lost their leaves and remain deciduous to this day.
     The Conifers though, along with a few other rebels, managed to stay green. All of them around here that is except for Bald Cypress. Having not drank of the magical elixir, it remains one of the few members of the Conifer tribe to lose its leaves. The beeches, oaks, and musclewoods did not have the benefit of the magical potion. They were battered by the wind and cold, some eventually losing their leaves, but most hung on.
     They knew if they held on long enough, the spirits of summer would eventually prevail. So they may lose their colors, lose limbs and some leaves, but they continue to rebel. So it is to this day that these trees retain their leaves, challenging the cold and wind, holding onto to the end of winter when they can. It is said that when the wind blows and tries to knock off the leaves, those who know the tale and remember the past know what is really happening and can hear what others do not. For if you listen to the rustling leaves hard enough, you can hear that what they're actually doing is laughing at the spirits of winter, secure in the knowledge that summer will one day again prevail, with the support of the allies among the trees...


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