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IPR News Radio's Sunday host, Cheryl Bartz, tells us what to look for as we wander around northern Michigan, helping us notice the little wonders all around us.

A Small Window

The fine, dark, horizontal lines on birch trees are lenticels. They are windows to the world that allow the interior of the tree to breathe. Photo Credit: Cheryl Bartz
Cheryl Bartz
The fine, dark, horizontal lines on birch trees are lenticels. They are windows to the world that allow the interior of the tree to breathe. Photo Credit: Cheryl Bartz

I’m always surprised when I notice for the first time something that I’ve seen thousands of times.

Case in point: the lenticel. Even if you’ve never heard of lenticels, I’m sure you’ve seen them.

How can I be sure? Well, I think you’ve probably seen apples, potatoes and birch trees.

Their lenticels are right there on the surface, out in the open, on display.

Let’s start with the birch tree.

I’ve always thought birch bark was beautiful. Those tiny, dark, horizontal lines contrasting with the white surface struck me as a visual design element that enhanced the appeal of the tree. But those tiny, dark, horizontal lines? Those are lenticels.

Nature doesn’t waste energy on things just for looks. Showy feathers and flowers have a purpose, and lenticels do, too.

They allow the interior of the tree to breathe. Lenticels are composed of ordinary bark cells, but they’re more loosely packed, which allows passage of carbon dioxide and oxygen.

They’re like little windows between the tree and the outer world. And these little windows are always open.

Leaves have openings, too, called stomata but they open and close, depending upon the needs of the leaves.

Lots of trees, fruits and vegetables have lenticels. Pull a carrot or potato out of the bottom drawer of your refrigerator and take a look. On the carrot, the lenticels appear as small, lens-shaped lines. On the potato, they are round dots. You can find them on apples, avocados, mangos, cherry trees— once you know they exist, you can readily see them. And if you can’t see them, you can feel them, if you have sensitive fingertips.

Cheryl Bartz hosts IPR's Sunday programming and writes a (mostly) weekly essay called "What's Up Outside?"