One of the most striking and well-known changes we see in plants are the brilliant fall colors of our deciduous trees, as they begin to lose their green chlorophyll coloring and reveal the striking yellow pigments underneath. The intense reds we see in our maples and sumacs are brought on by sunlight and cold temps, causing chemical changes in glucose left in the leaf after photosynthesis stops. Some trees, like many of our oaks, will retain their dead leaves all winter, and won't drop them until new leaves unfurl in the spring, a characteristic called "marcescence". Many other tree species, like the black walnut, have already shed their bright aura for the fall, so be sure to get out and enjoy those vivid forests and ridgelines before all the autumn colors have fallen to the forest floor!
Beneath the bark, there are other subtle changes happening, too. Trees are beginning to send the sugars they have created through photosynthesis into their root system for the winter. They'll use these sugars again next spring to start the growing season off with new leaves.
Herbaceous plants growing on the forest floor have other ways of dealing with winter.
What we call Annuals are plants that complete their life cycle and die all within one growing season, leaving their seeds behind to start the process all over again the next year.
Many others, including Perennials, Shrubs and Trees slow their growth significantly and survive the winter off of food they've produced during the growing season. While many herbaceous perennials appear to die off above ground, they retain life in their roots or bulbs until the spring.
While most wildflowers have long since blossomed, some species specialize as fall bloomers, including members of the goldenrod and aster families. Look for these beautiful yellows, whites and purples in fields and meadows around Central PA.
Of course, this is also the time of year when our local farmers and gardeners are reaping some of their last crops for the season, and are busy storing, freezing or canning vegetables for the winter ahead. I invite you to come out to Shaver's Creek this weekend, October 22 and 23 to celebrate autumn at our annual Fall Harvest Festival featuring the Children's Halloween Trail. Visit ShaversCreek.org for more information.