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Marcescence

Posted on by Jesse Freeman (Upstate)

Photo Credit: Jeanne Malmgren

by Jeanne Malmgren

 

On my mind this time of year are …. beech leaves. And the fine art of letting go. Which brings us to the title of this post.

Marcescence (mar-SESS-ents).

What a lovely word! Let it roll around in your mouth for a minute. Whisper it. Say it aloud. Maybe even sing it. There’s a melody there, don’t you think?

Marcescence has a scientific definition, which I won’t bore you with. You can look it up. In essence, it’s the ability of certain plants and trees to hold on to their leaves long after all their neighbors have given up.

The surrounding forest is bare, cold winds are whistling, hibernating animals are deep asleep … but a marcescent tree will be holding onto its leaves for dear life. Like a stubborn kid who won’t give up his blankie to the inevitability of the washing machine.

Marcescent trees do this, supposedly, for several reasons (brilliant reasons!):

  • Deer and other browsers don’t like nibbling on twigs and tiny new leaf buds when scratchy old dry leaves are in the way.
  • When a marcescent tree finally drops its leaves in spring, that’s a rich source of fresh compost (aka food!) for the newly-budding-out tree.
  • That carpet of newly-shed leaves also suppresses springtime understory growth that would compete with the tree for space and nutrients.

American beechs (Fagus grandifolia) aren’t the only trees that exhibit this botanical oddity. Several varieties of oaks do it, as well as hornbeams and witch-hazel. But let’s face it: Beeches have a leg (branch) up on all the others.

Beeches are the glimmering stars of the winter wood. When everything else has gone gray and the forest is a muted palette, beech trees wave for attention, their dessicated leaves glowing golden/bronze/amber.

Photo Credit: Jeanne Malmgren

A walk among beeches on a January day is an uplifting experience.

Beeches do one other interesting thing in winter: They shed some of their leaves, but not all.

Here’s “Beechie,” who lives in our backyard. (Yes, Jim and I are fond of Beechie. He stands alone at the edge of the treeline, as if he wants to be near us. So of course he deserves to have a name.)

Photo Credit: Jeanne Malmgren

Every year Beechie performs this ritual: When other deciduous trees start to shed their leaves, he does too. But only his top half. As fall slides into winter, Beechie’s upper branches are suitably bare. The bottom half retains its leaves, an orange-brown skirt that persists long past the last freeze date, when new leaf buds appear on the upper branches.

All of this begs the question: How does a beech tree know when to drop those last leaves … and which ones?

When is it time to let go?

 

 

Note: This article was adapted from a post in Jeanne’s excellent online newsletter, Rx Nature. You can subscribe for free at jeannemalmgren.substack.com.