I was hanging out on my parents' back porch the other day, just watching the leaves kind of bobbing around in the breeze. And, something about the maple closest to the porch caught my eye.
Here is a photo of it. Look at the bark. Look at the pattern of where it is rough and where it is smooth. Does that remind you of anything?
Stretch marks! LOL! I wondered whether I was crazy to think that...but, look at the smooth part and then the lines of cracked bark.
Anyway, I was interested enough to look it up. And sure enough, I found out that trees with smooth bark, like the birch tree, have bark that is elastic. It stretches and stays smooth as the tree grows.
Other trees have rough bark because it is not elastic, so it cracks and "heals" as the tree grows. The maple that I have photographed apparently has fairly smooth, fairly elastic bark. It only cracks some of the time.
Here is a photo that really illustrates this. See how there is cracking down on the part of the bark where more growth has occurred? But, on the narrower branches further up the bark is smooth?