My kids and I were heading to school the other day amidst a flurry of falling leaves. Our property is a small city lot, but it is surrounded by six, giant, 80-year-old silver maples. Their branches reach high into the sky, providing a shady canopy to our yard and playground to the woodpeckers, raccoon and squirrels that live in the neighborhood. The best Sunday afternoon includes curling up in bed with a good book and a daydream while gazing out at those gracefully arching branches.
But on this cool autumn day, the leaves were showering down around us, swirling and dancing in the light breeze. It reminded me of a couple days earlier when the kids had raked up the leaves in my brother’s yard only to throw them high in the sky. As the bundles rained down upon them, they danced and laughed and shouted with glee. The falling leaves seemed like an invitation to come out and play. To dance in the wonder that is fall.
So, I wondered, why are the leaves falling with a flurry right now? The science behind falling leaves says that there is a layer of cells called ‘abscission’ or ‘scissor cells’ that exist at the base of each leaf. When the days shorten and the temperature drops, the tree pulls its food energy (in the form of sugar water, or glucose) back into the trunk and roots of the tree. As this happens, the abscission cells begin to grow over the stem base, separating the leaf from the branch and cutting off the tubes that carry glucose between the leaf stem and the branch. As the leaves lose glucose (remember glucose consists of sugars and water), the chlorophyll (which is responsible for a leaf’s green color) disappears and the leaves begin to display their brilliant autumn colors. Once the abscission cells have completed the task of sealing off the node (or that point that joins leaf to twig) and of cutting the leaf’s connection to the tree, it takes just a gentle puff of wind to send the yellow, red and crimson leaves floating through the sky.
The trees are readying themselves for winter. They are pulling their energy inward and are beginning their own form of hibernation, which will enable them to survive the harsh, cold winter. Much like we do with our own families in our own houses. But on the days when the sun shines forth and the leaves rain down… I will grab my children, run outdoors, look up into the branches and dance.