Archive for September 15th, 2014

Nature: Why Leaves Turn Color in Fall

Monday, September 15th, 2014

Trees along a lake, changing color for fall.

Fall foliage at Daingerfield State Park

This is Passport to Texas

‘Tis the season when we see foliage turn colors. If you’re like me, you wonder why, and what purpose it serves.

13— Right. It’s kind of like, why is the sky blue type question. But the interesting thing about fall color is it doesn’t really have a purpose. It’s the result of some chemical processes that occur in the leaf.

Damon Waitt (WAIT) is director and senior botanist at the Ladybird Johnson Wildflower Center in Austin.

11— When you think about being a leaf during the wintertime… it’s not a good time to be a leaf. Especially if you’re a thin flat one. Because, cold temperatures are going to kill that leaf.

So, these trees cut their losses as seasons change.

21—They want to capture all those good chemicals out of the leaf before winter and put them back in the tree and store them in the roots. And so that’s what they start to do when the nights get longer, which is a signal that winter is coming. A consequence of that is the leaf is no longer making chlorophyll; other pigments start to show up.

Damon Waitt likens this process to recycling.

17—Yes, trees are great recyclers. They don’t want to waste all those great chemical compounds that are out in the leaf that have been doing work all summer long, and in the spring, causing the plant to grow. So, they recycle the chemicals they can, and then dispose of the leftover material that’s in the leaf.

That leftover material is what you rake every fall. More fall foliage tomorrow.

For Texas Parks and Wildlife, I’m Cecilia Nasti.