[NOTE: If you recall back on October 14, “Friday Fun” was MIA. This is the story that I was planning on doing at that time – but other events interceded.
[As you can see by this helpful Fall Foliage Interactive Map, (using the sliding date bar at the bottom) most of the country is probably “Past Peak” – but since Fall is my favorite time of year, I’m redoing it.]
Seems logical that the best way to begin an overview of the story behind fall’s phantasmagorical foliage fling is with … well, an overview of the vast verdant vegetation of the vales and vistas of Vermont.
So Let’s Revisit Why Leaves Change Their Colors
We all probably recall some grade school science about leaves and chlorophyll and color – but let’s take a little closer look.
While both humans and trees enjoy eating, trees are unique in that they’re actually able to manufacture their own food, courtesy of photosynthesis. (But being able to make your own food supply makes me wonder why we don’t see more fat trees. I mean, come on …)
Chlorophyll is the green pigmented chemical in leaves that uses the energy provided by the sun to convert water from the trees’ roots and carbon dioxide from the air into sugars and starches that the tree stores as nutrients – and with oxygen as a by-product. (You paying attention to this, Sen. “Global-Warming-Is-A-Hoax” Inhofe?)
But the chlorophyll that gives trees their green is not the only colored pigment present all the time in leaves. Working just as hard in the leaves are the carotene and xanthophyll chemical pigments – they’re just masked by the overpowering chlorophyll.
But with the coming of autumn, as daylight hours shorten and temperatures cool down, the veins that carry fluids into and out of the leaf gradually become closed off by a layer of special cork cells that forms at the base of each leaf. As this cork layer develops, water and mineral intake into the leaf becomes diminished, and so chlorophyll begins to decrease.
These carotenoids give their characteristic oranges and yellows to carrots, corn, canaries, and daffodils – along with egg yolks, rutabagas, buttercups, and bananas. And they account as the predominant color in about 15-30% of our tree species – typically the hardwood species of hickories, ash, maple, yellow poplar, aspen, birch, black cherry, sycamore, cottonwood, sassafras, and alder.
But some colors – specifically the reds and purples of anthocyanin – have not been present all along, but just hidden by the chlorophyll like carotene and xanthophyll. The anthocyanins are created brand new – just for autumn’s fall foliage!
In the summer, phosphate levels in the leaves are elevated, as they are used to breakdown the sugars for energy that were produced by chlorophyll. But come fall, phosphate (as well as other chemicals and nutrients) move out of the leaf itself and into the stem. So sugar-breakdown chemisty changes, which leads to the production of anthocyanin pigments.
And the brighter the sunlight during this period, the greater the production of anthocyanins – and the more brilliant the resulting reds and purples. This more-or-less direct proportion to sunlight exposure explains why the periphery of some hardwood trees are bright red, while the foliage lower down and inside are the more typical oranges and yellows.
Anthocyanins also account for the coloring of cranberries, red apples, blueberries, cherries, strawberries, and plums. They are present in only about 10% of hardwood species – namely, the maples, oaks, sourwood, sweetgums, dogwoods, tupelos, cherry trees and persimmons. But in certain lucky areas — most famously New England — up to 70% of tree species may produce the anthocyanin pigment.
Time to enjoy some of my favorite photos of the fantasia of Fall …
And if you’re as lucky as this little guy to enjoy a snack while leaf-peeping, you may also be literally bowled over by the beauty of autumn’s Fall foliage …
12 Responses to “Friday Fun – Who Knew Biochemistry Could Be So Beautiful”
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COMING "FRIDAY FUN" ABSENCE NEXT TWO COMING FRIDAYS
Next Friday will be my Mom’s 100th Birthday! So I’ll be up in Illinois to celebrate it with her and my aunt.
But to accommodate her grandson (my nephew) and his family (she wants to see her two great-grandsons … who can blame her?) who live in the San Francisco Bay area, we’ll all be getting together for an Open House celebration at her church on Saturday, November 19th, as the boys will be out of school that week for Thanksgiving.
A little inconvenient for me having to make two 900+ mile RT treks in a week’s time – but this is pretty special, and my brother (Tampa Bay) and I have lot more flexible schedules than they do.
Please give your Mother a Happy Birthday wish from me, that is so wonderful, reaching 100, and still able to crack the whip with her boys!
Wow, your mother will be a 100 years old next Friday! That's so remarkable. Celebrating a century of life is well worth traveling 900+ miles four times in a week. You may have considered staying in Illinois between the celebrations, but that would take you away from home for over a week, I guess. So enjoy your trips, both celebrations and a great family reunion in honor of your favorite centenarian. Please congratulate her for me and for yourself: take care and stay safe and see you here in three weeks time.
Cross posted to Care2 at http://www.care2.com/news/member/101612212/4019394
Growing up in the San Francisco Bay Area, where the vast majority of trees don't change and those that do, do so feebly, since the temperature seldom drops below 35F, I used to think the photos of almost neon leaf colors were – well, whatever stood in for photoshop then. A transfer to North Carolina taught me how wrong I had been. And your explanation explains why some of the leaves become such a dark red – burgundy and royal purple. I knew about pigments being present under chlorophyll, but never knew that not all of them did, and wondered how the chlorophyll could mask colors so dark. But it doesn't have to. Your alliteration, BTW, is almost groanable.
Just "almost groanable"?
Rats … I'll have to work harder at.
Actually I was trying to be "tactful." You really did go over the top. Starting with "f" sounds, then going to "v" which is the same sound voiced, was brilliant.
Do have great travel – and don't get too exhausted. We need you.
Great educational post. I am saving this one.
Every autumn, my family would load up in the car, and we would go to the Poconos to see the foliage and the magnificent colors of the trees. So enjoyed those annual trips, and have fond memories of them.
The Great Smoky/Applachian Mountains (trails), also has some wonderful views as well.
Happy Birthday to your mom, and safe trips, to and returns to you too! Thank you for your post, Nameless, and Joanne for cross posting.
WOW, Nameless!!
Have two great trips.
The video almost looks like Eastern Kentucky, our mountains have been lovely but are past their peak now. I have a hill in my back yard, lots of dogwood and red bud trees, poplar, beech, and scrub pine. It has been purple,red, gold, and green, making me love to sit on my back porch. Thanks for the information.
Forgot, loved the squirrel!
Thanks for the glorious colors and delightful squirrel, Nameless. It brings back lovely memories to the time we went leaf-peeping in New England around this time of year, many years ago. When we traveled along the Appalachian and Smoky Mountains in summer some years later, we made plans to come back there some autumn to watch the colors turn there too, but never got around to it. I think we will get there eventually, because one of the thing I'm going to miss living in subtropical Queensland is the distinctive change of seasons and especially the color splendor of autumn.