Part 1 in a new miniseries "Leaves"... It's true, they're not much more than solar panels for plants. Except that they're also absolutely gorgeous, especially this time of year. We'll be exploring leaves in the fall with the next 5 posts. We could all stand to learn a little more about Nature, so stay tuned, and post a picture of an even yellower leaf! (or explain to the rest of us why they turn so yellow). You'll learn more at www.landexplained.com
Part 2: "Leaves". Un-be-leave-able! Did you know grass and wildflowers can put on just as good a fall color show as the trees do? In the high country, all it takes is the first chill rains of September to make the chlorophyll break down in the leaves, and reveal the underlying yellow (xanthophyll), orange (carotene), and red (anthocyanin) colors. Tree, shrub, grass, or flower--these pigments aren't just for show: the yellow acts as a kind of sunscreen, the orange shuttles energy from the chlorophyll and protects the cell from radical oxygen, and the red just might be protecting cells from temperature extremes. Hard to believe, but all that beauty is just an accident!
Autumn leaf eye-candy, and part 3 in the Leaves miniseries. My prescription for how to leave behind all your troubles? (did you catch that pun??) --sit by a stream and watch the water move on by. Seriously, those leaves are the trees' donation to the food web. It's called allochthonous material for the ecologists among you, and is the original source of stream nutrients for those of you who fish. For the rest of us, it is just plain beauty in motion, and a metaphor for washing away life's trials and tribulations.
Part 4... "Leaves". In an ironic twist, this oak leaf finally stands out as an individual just as all its cells are shutting down. Cut off from its tree and nourishment, the leaf gets to express itself--allowing some spots to die before others, some pigments to remain and others to degrade as it shuttles resources around--creating a variation on the oak leaf theme that's as unique as any snowflake. The juniper needles look on from the sidelines, scale-like leaves all uniform and gray-green. But their time will come, although it may take a decade for the oldest ones to redden and fall off the stem. Different approaches to the same ends-- mother tree just can't afford to support worn out and vulnerable parts, so sooner or later, she turns over a new leaf, so to speak.😉
Part 5 in the Leaves miniseries. There's something about the fall sunshine that's so poignant. It's got such a hollow feel to it, and leaves those dark, cold shadows. Internet experts point out the physical facts: with the sun lower in the sky, its rays have to pass through more of our atmosphere, which scatters off more light, and even more of the shorter blue and purple wavelengths. What's left behind is thinner and redder, and shorter in duration. That's what makes the leaves' inner clock--a chemical called phytochrome--kick in with a message to the tree: "seal off the leaves!" The stems promptly start building a corky layer of cells which cut off all trade between tree and leaf, and the leaf is history!
Part 6, Leaves Miniseries. The other half of autumn leaves. We get so caught up in the blaze of fall colors, that we forget to look down and see the tiny, bright green seed leaves at our feet. Chilly fall rains often kick off the leaf-dying process in many perennial plants. But these same rains also trigger seeds to germinate for winter annuals and other adapted plants. They've figured out how to take advantage of the positives of seasonal changes--more moisture, less competition, more light as overhanging leaves wither and die--and minimize the negatives. Those negatives center around the very cold and dark associated with the cutback in sunshine which causes delicate tissues to freeze, chlorophyll to degrade, and plants to scramble to seal off and safely drop their leaves. How do these tender young leaves escape it? By staying small and lying low, preferably under a blanket of snow. And by taking a lot of preventative measures at the micro-level that involve sap, membrane proteins, and intracellular water extraction.
So, for myself and the many others who feel that autumn is the sorrowful season, we should look down, and take heart. That promise of rebirth is there looking back up at us, so vital and full of the will to survive that it's gone to incredible evolutionary lengths to rearrange how things are done. And that, in a final, unforgivable pun, "leaves" me speechless.
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