From the brains behind brains on, this is the moment of um.

Answering those questions that make you go. Oh, um, um, uh, uh, and uh, uh, and uh, and up, uh,

and uh, uh, and up, uh, and up, uh, and uh, uh, and stuff,

and uh, and stuff, and uh, and uh, that, um, the moment of um comes to you from a

uh, I'm, uh, uh, uh, uh,

um, the moment of um comes to you from a p.m. studios. I'm Molly Bloom. Can you tell how

old someone is just by looking at them? I mean you can see if someone's a kid or a

grown-up, but it's hard to know exactly how many years old they are unless you ask.

But when it comes to trees, if you open them up, you'd see they have rings inside their trunk,

and we can usually tell about how old they are by counting those rings or can we?

One of our listeners was curious.

My name is Chris and I'm from St. Louis, Missouri.

My question is how does you make rings inside and do the rings really show the tree's age?

The tree rings are produced by the vascular cambium. And the vascular cambium is this really thin wafer like layer of cells

and it grows in both directions.

So my name is Diana Masias. I am a PhD student at the University of New Mexico.

I am a forest ecologist that studies how different populations of trees respond to drought.

Towards the outside of the tree, it builds the phlegum, that sugar pipeline that moves the sugar throughout the tree,

and then towards the inside of the tree throughout the tree. And then towards the inside of the tree,

towards the center, it grows the xylem,

which is the water pipeline of the tree.

And that's actually the tree ring.

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