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Speaker 1: Welcome to Brainstuff, a production of iHeartRadio. Hey brain Stuff,

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Speaker 1: I'm Lauren vogele Bomb. And this is another classic from

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Speaker 1: our archives. This one details why evergreen trees like pines

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Speaker 1: and many other conifers get to keep their green leaves

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Speaker 1: year round, seemingly thumbing their nose at seasonal changes. Hey

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Speaker 1: brain stuff, lourenvogel Bomb. Here, evergreen trees seem to thrive

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Speaker 1: during the colder months, steadfastly holding on to their brightly colored,

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Speaker 1: needlelike leaves as temperatures plummet, bringing welcome color and contrast

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Speaker 1: to snowy landscapes. On the other hand, the wide and

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Speaker 1: flat leaves of their deciduous counterparts transform into brilliant shades

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Speaker 1: of red, orange and gold during the chilly and dry

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Speaker 1: days of fall and early winter, only to eventually shed

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Speaker 1: Their branches will remain barren until spring. So why are evergreens,

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Speaker 1: which include many, but not all coniferous trees such as pines, firs, junipers,

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Speaker 1: and spruces, is immune to seasonal leaf changes in shedding,

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Speaker 1: while species of deciduous trees like aspens, birch, cherry, oak,

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Speaker 1: and maple aren't. It mostly comes down to a little

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Speaker 1: thing you might have learned about in biology class called photosynthesis.

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Speaker 1: Both deciduous and evergreen trees use energy from the sun

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Speaker 1: and water from the ground to turn carbon dioxide in

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Speaker 1: the air into food. The difference is that shorter days

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Speaker 1: brings less sun during the fall and winter, and that

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Speaker 1: translates into less energy. So deciduous trees bearing broad, flat

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Speaker 1: leaves go dormant or into a sort of hibernation mode

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Speaker 1: and shed their leaves to help them conserve water and

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Speaker 1: stay alive until spring arrives and new leaves grow from

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Speaker 1: new buds. Evergreens, meanwhile, boast needles that are actually tightly

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Speaker 1: rolled leaves, and the low surface area of this shape

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Speaker 1: helps the needles conserve water throughout the fall and winter.

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Speaker 1: A waxy coating on the needles also helps keep water

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Speaker 1: from evaporating. Compared with broad delicate leaves, These dense waxy

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Speaker 1: needles resist cold and stay moist, which keeps them green

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Speaker 1: throughout the winter. But evergreens actually do shed their needles,

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Speaker 1: just not all at once. As needles age, they turn

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Speaker 1: yellow brown or a reddish tan and will fall from

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Speaker 1: the tree, but usually only a handful at a time.

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Speaker 1: The trees are constantly growing new needles so they can

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Speaker 1: stay green year round. Evergreens greater leaf longevity means they

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Speaker 1: can survive in environments that don't work for their deciduous cousins.

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Speaker 1: In fact, evergreens can be found on every continent except Antarctica.

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Speaker 1: The bottom line is that although those colorful deciduous trees

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Speaker 1: attract their share of seasonal leaf peepers, trees that stay

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Speaker 1: green year round add character to people's yards during the

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Speaker 1: fall and winter, offer shelter to birds and small animals

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Speaker 1: when the winter is cold, and many species are dense

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Speaker 1: enough to serve as windbreaks and privacy screens. Today's episode

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Speaker 1: is based on the article why evergreen trees don't shed

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Speaker 1: their needle like leaves on HowStuffWorks dot com, written by

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Speaker 1: Windy Bellman. Brain Stuff is production of iHeartRadio in partnership

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Speaker 1: with how stuffworks dot Com and is produced by Tyler Klang.

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Speaker 1: Four more podcasts my heart Radio, visit the iHeartRadio app,

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Speaker 1: Apple Podcasts, or wherever you listen to your favorite shows.