Soon the leaves will start cringing on the trees and roll up into clenched fists before they begin their seasonal drop. Dry seedpods will rattle like tiny gourds up in the canopy of trees and fall will soon be upon us. Trees are like people, with no two alike, and one species of tree can have many variations when it comes to the fall coloring of foliage.
Where do the colors come from? When the days begin to shorten, soon after the summer solstice (June 21), a tree reconsiders its leaves and their future.
All summer long the tree feeds the leaves so they can process sunlight, but in the dog days of summer the deciduous trees begin pulling nutrients back into their trunk, branches and roots. Undernourished, the leaves stop producing the pigment chlorophyll, the process of photosynthesis ceases and other pigments enter into the trees’ anatomy.
Animals can migrate, hibernate or store food to prepare for winter. But where can a deciduous tree go? It survives by dropping its leaves, and by the end of autumn only a few fragile threads of fluid-carrying xylem hold leaves to the stems.
Trees have their own recipe of development and growth and it is fascinating to follow their foliage color changes. Then all of a sudden, with a light breeze, the leaves are airborne and flutter down to the earth.
Not all leaves turn the same color. Elms, weeping willow, the ancient ginkgo, aspens, cottonwoods and alders all produce radiant vibrant yellows; our native sycamores can have variations of bronze, copper and gold.
Some of the other colorful fall trees are maples, birch, eastern redbud, maidenhair tree, honey locust, Chinese flame tree, crape myrtle, persimmon, Chinese pistachio and the tallow tree. The tallow tree (Sapium sebiferum) can turn flaming red, plum-purple, yellow-orange or mixed colors and it puts on a pretty great display.
Liquidambar, which is planted throughout the southland, has some cultivars that have been selected for additional fall colors in their foliage. Some of those cultivars for added colors are “Burgundy,” “Festival” and “Palo Alto.”
Another unique American sweet gum is “Rotundiloba.” This selection of liquidambar has rounded leaves rather than sharp-pointed lobes, does not set the traditional round seedpods and is fruitless.
With a short tour up to our local mountains, you can enjoy additional color when the deciduous oak foliage starts its seasonal color change.
Fall is also a good time to go to your local nursery and check out the foliage and make selections that fit your garden décor. Travel from nursery to nursery in your area to see what is available, for the fall season really is the beginning of the wonderful holidays to come.
“Trees nourish our soils. The best time to plant a tree was 20 years ago; the next best time is today.”
Roger Boddaert is a Certified Arborist and a professional landscape designer. He can be reached at (760) 728-4297.
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