In our neck of the woods... bendy trees versus brittle trees.

This past summer, a tornado tore through our area. Fortunately for us—but not for some of our neighbors—the worst damage was about a quarter mile away. On two hill ridges near our house, countless trees were blown down. Some of them broke off, others were torn out out of the ground, roots and all.

When I was hiking through that area observing the devastation, I came upon this large tree than had fallen down on this smaller tree, bending the smaller tree completely over. Without breaking it.

How in the heck did this tree NOT break?? At the time, I didn't think to try to identify the tree species. Now that I examine the photo, I see that the larger fallen tree is a shagbark hickory, and I think the smaller bent tree is an oak, but it could also be an ash. Both ashes and oaks are hardwoods and are strong, but ash wood is known to be more flexible and can be bent (with the help of steam) to make chair backs and such. I suppose it helps that this is a younger tree, but this tree is far larger than a sapling (at least 7 inches in diameter at the bend), so this degree of flexibility seems extraordinary to me.

Okay, without going too far down this rabbit hole, let's briefly consider why some trees can bend without breaking. A lot of it has to do with three substances: cellulose, hemicellulose, and lignin. The cell walls of wood cells are made of these three substances, and the proportions of these three substances can determine how flexible the wood is.

Cellulose is basically very strong fibers. Lignin is like a rigid glue that holds things together. And Hemicellulose is like a flexible web that surrounds and links cellulose fibers and lignin (apologies to the real botanists out there for oversimplifying). Trees that have more hemicellulose are typically more flexible. Trees that have more lignin are rigid and strong.

Young trees have more hemicellulose and are therefore more flexible. Older trees have more lignin, which makes the wood harder and less flexible.

Obviously, the young tree in this photo has a LOT of hemicellulose!

That's your fun tree lesson for the day.