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

Answering those questions that make you go.

The moment of um um comes to you from APM Studios. I'm Molly Bloom. Autumn is one of my favorite times of year, pumpkin spice lattes, cozy sweaters, and crunching through the fallen leaves

in the yard. After all the green trees turn brilliant chains of

orange, yellow, and red, they gently waft to the ground where they can be scooped into giant

piles just perfect for jumping in. But you know who doesn't get in on the leaf party? Evergreen

trees. Those include pines, furs, and spruces, and they have needles instead of leaves. One of our

listeners wanted to know what happens to them.

My name is Eva from Michigan.

My question is, why do pine trees not lose their needles in the winter,

like how other trees lose their leaves?

So leaves are very expensive to make.

My name is Diana Macias.

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.

There are a lot of different strategies that different plants have evolved to deal with these costs.

And so some trees like deciduous trees make new leaves every year,

whereas some trees like evergreen trees trees invest a lot in their needles

and retain them or keep them. So those are the trees that don't lose their needles. In addition to

energy costs is water preservation. So in the winter, when trees stop photosynthesizing,

they want to reduce the amount of water they also lose.

Deciduous trees will drop their leaves

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