Tuesday, December 6, 2016

Abscission

I learned so much about the biological workings of large plants in this book by Peter Wohlleben The Hidden Life of Trees.

He makes gleeful, joyous observations about how trees communicate and how they sense their environment and how they even remember and maybe even feel.

Some of it is speculation, a lot is yet to be proven, but much of it is established science that he writes about in a way that a gardener like me can enjoy.

Like the process of abscission -- he tells us that when trees get ready to drop their leaves for winter, they first have to create two layers of cells in between the leaf and the stem.

A chemical process reacts to shorter days (think about this, a tree has to "tell time" by reacting to how long the light is and "remember" that yesterday was shorter than a week ago and somehow store that information chemically in its being. . .  this boggles. . . )

When the tree tells what time it is and remembers how long each day has been, and gets ready to shed leaves, or abscise them, it forms a layer of cells with weak walls. Then it forms a layer of bigger expanding cells near the stem. When the big cells expand they break the weak cells open and the leaf comes off.

It takes time to grow these cells in fall. If an early frost freezes the leaf before the cell layers have grown, the tree can't get rid of its leaves. It's too late to grow the expanding cell layer and the weak walled cells.

Japanese maples often get caught without enough time. They freeze here before they can abscise, and then the brown dead leaves end up hanging on the tree all winter. There is no expansion layer to push the weak layer off.

I've despaired about that with my Japanese maples in some winters.

Oaks and young beeches choose not to abscise their leaves on purpose. They use a whole other strategy for getting through winter.

But the trees that do drop go through a specific, timed process to make that happen.

And I've been thinking about that process a lot lately. If Wohlleben can write about the human-like lives of trees, is it a stretch to think about the botanical-like parts in us?

Is it stretch to realize I am just now growing cells, creating separation layers that will allow me in a year or two to abscise my garden and all that I have grown in it?

We will move in the future and I will leave this garden. We are planning and getting ready, and I feel myself now building emotional distance -- a layer that will let me be rid of what has been so important to me when I say goodbye to my garden and move west some day.

I'm not ready yet. It's taking some time. I have to go through a process of growing those layers first, but I can feel it just as surely as the trees outside my window grew their own cells of separation for winter.

1 comment:

  1. This is a beautiful post, and a further spur to arrange for Santa to put this book under my tree. I'm winter-planning today -- ground too frozen to get in the last of the bargain daffodils -- and your blog is providing hugely instructive as well as inspirational.

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