Welcome to brain Stuff production of iHeart Radio, Hey brain Stuff Lauren vogebam here. Evergreen trees seem to thrive during the colder months, steadfastly holding onto their brightly colored, needle like leaves as temperatures plummet, bringing welcome color and contrast
to snowy landscapes. On the other hand, the wide and flat leaves of their deciduous counterparts transformed into brilliant shades of red, orange and gold during the chili and dry days of fall and early winter, only to eventually shed
Their branches will remain barren until spring. So why are evergreens, which include many, but not all, conniferous trees such as pines, furs, junipers, and spruces immune to seasonal leaf changes in shedding, while species of deciduous trees like aspens, birch, cherry, oak, and maple aren't. It mostly comes down to a little thing you might have learned about in biology class called photosynthesis.
Both deciduous and evergreen trees use energy from the sun and water from the ground to turn carbon dioxide in the air into food. The difference is that shorter days brings less sun during the fall and winter, and that translates into less energy, so deciduous trees bearing broad flat leaves go dormant or into a sort of hibernation mode, and shed their leaves to help them conserve water and stay alive until spring arrives and new leaves grow from
new buds. Evergreens, meanwhile, boast needles that are actually tightly rolled leaves, and the low surface area of this shape helps the needles conserve water throughout the fallen winter. A waxy coating on the needles also helps keep water from evaporating compared with broad, delicate leaves. These dense, waxy needles resist cold and stay moist, which keeps them green throughout the winter. But evergreens actually do shed their needles, just
not all at once. As needles age, they turn yellow brown or a reddish tan and will fall from the tree, but usually only a handful at a time. The trees are constantly growing new needles, so they can stay green year round. Evergreens greater leaf longevity means they can survive in environments that don't work for their deciduous cousins. In fact,
evergreens can be found on every continent except Antarctica. The bottom line is that Although those colorful deciduous trees attract their share of seasonal leaf peepers, trees that stay green year round add character to people's yards during the fall and winter, offer shelter to birds and small animals when the winter is cold, and many species are dense enough to serve as wind breaks and privacy screens. Today's episode was written by Windy Bowman and produced by Tyler Clang.
The brain Stuff is production of iHeart Radious How Stuff Works. For more in this and lots of other evergreen topics, visit our home planet, how stuff Works dot com. And for more podcasts from my heart Radio, you can visit the iHeart Radio app, Apple Podcasts, or wherever you listen to your favorite shows.