#47 (12-05-18)  _ IMG_6900 - Chinese tallow color.jpg

Trees and other plants along highways and home landscapes have provided a respectable display of fall color over the past weeks. Although Chinese tallows are considered an invasive tree species, they have provided eye-catching displays of fall color. In Colorado, it’s the gold of aspen trees that catches the eye. In New England, it’s the brilliant oranges and yellows of the sugar maples.

Each fall, a glorious spectrum of colors blankets the hardwood forests in many areas of the United States. I grew up on a family farm located in South Central Virginia and I looked forward to the fall season every year. Each fall, the area would be covered in a quilt of colors so vibrant that even a teenager would likely take notice.

In Colorado, it’s the gold of aspen trees that catches the eye. In New England, it’s the brilliant oranges and yellows of the sugar maples. And in the South, it’s the deep scarlet of the red oaks, the reddish-orange of sumac and the multicolors of sweet gum.

Despite appearances, Mother Nature doesn’t paint with broad brush strokes. Paint-by-numbers would be a better analogy because each tree has its own fall color bound up in the chemical composition of the sap, which provides the “instructions” on what color to turn.

Tree leaves change colors according to complex chemical formulas. Depending on how much iron, magnesium, phosphorus or sodium is present in leaves and the acidity of tree sap, leaves might turn amber, gold, red, orange or just fade from green to brown. Scarlet oaks, red maples and sumacs, for instance, have a slightly acidic sap that causes the leaves to turn bright red.

The leaves of ash trees growing in areas where limestone is present will turn a regal purplish-blue. What prompts the change? Although many people believe that a mischievous Jack Frost is responsible for the color change, weather conditions are just one factor at play. As the days grow shorter and the nights longer, a chemical clock inside the trees starts up, releasing a hormone which restricts the flow of sap to each leaf.

As the autumn season progresses, the sap flows more slowly and chlorophyll, which gives most leaves their basic green color over the spring and summer seasons, starts to disappear. The residual sap becomes more concentrated as it dries, creating the colors of fall.

In other words, the colors are always there, but as the predominant hues of green fades, other colors become enhanced and begin to show through. Sunlight, nutrients and moisture level factor into the process and cool weather seems to slow things down to bring out the full effect.

Obviously, this area is not a hot spot for fall color along the roadways as we don’t have the aspens of Colorado nor the sugar maples of New England. Along the highways in Galveston County — well, it’s basically the orange, yellow and red hues of the maligned Chinese tallow and a few other trees.

I was pleasantly surprised to see one tree species providing an unexpected burst of fall color. Last week while walking back to my office from the Discovery Garden in Carbide Park in La Marque, I noticed a colorful layer of fallen leaves below the canopy of a Texas ash (Fraxinus texensis). The leaves from this tree were a striking yellow-gold in color but leaf colors in the fall also range from gold, orange and purple depending on local conditions. The crape myrtle in my backyard produced a maze of yellow, red and copper colored leaves that provided a glimpse of fall color. A few blocks from my home is a neighbor’s mature and very tall bald cypress. I have witnessed the tree’s foliage turn from a soft green to a striking bronze color over the pass weeks as I drive to work.

Yes, fall colors in our urban forests along the Texas Gulf Coast do not hold a candle to those in many other areas of the nation. However, it seems that life is often about trade-offs — in this case, I find ample solace and much happiness in living in an area with very mild and pleasant winters.

Seminar on The Jewels in the Garden … Hummingbirds

Galveston County Master Gardener Deborah Repasz’s presentation will include the fight and flight for survival of hummingbirds in Galveston County. Repasz will highlight ways to increase hummingbird sightings in your yard by creating an inviting habitat using shelter, food, and water. Plants, including Texas natives, and other resources that attract hummingbirds will be presented, as will the impact of pesticides on hummingbirds.

The seminar will be conducted on Saturday, Dec. 8, from 1 p.m. to 3 p.m. at the Galveston County AgriLife Extension Office located in Carbide Park, 4102-B Main St. in La Marque. Pre-registration is required by phone 281-309-5065 or e-mail galvcountymgs@gmail.com to ensure the availability of handouts.

Master Gardener Class Applications

Applications for the 2019 Master Gardener class are due on Thursday, December 6. Applications can be picked up at the Galveston County AgriLife Extension Office located in Carbide Park, 4102-B Main St. in La Marque or downloaded online https://aggie-horticulture.tamu.edu/galveston/. Classes will be held from Tuesday, Feb. 5, and on each Tuesday and Thursday thereafter through April 11.

Dr. William Johnson is a horticulturist with the Galveston County Office of Texas AgriLife Extension Service, The Texas A&M System. Visit his website at aggie-horticulture.tamu.edu/galveston.

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