Painting the Town Red, Yellow, Orange, and More
Is it too soon to talk about autumn? I feel like it’s too soon, but this heat and humidity has me longing for cooler days and longer nights. So I’ve decided it’s a perfect time to talk about the upcoming season.
Autumn is just around the corner and that means so is apple cider, maple donuts, pumpkin pie, and of course the trees in their full glory. This is by far my favorite time of year. There is a crispness in the air, a scent of wood-burning camp fires, the rustling of fallen leaves underfoot, and rich, bold colors everywhere you look. The reason why leaves change their colors this time of year is complicated, and scientists still don’t fully understand each and every interaction that determines the best displays of colors. However, they do know that the pigments in the leaf, the longer nights, the type of plant, the cooler weather, as well as the amount of rainfall, all play a significant role.
All plants contain pigments in their leaves. Three of these pigments are very involved in the color changes of autumn. They are chlorophyll, which gives leaves their green color during the growing season; carotenoids, which provide yellows, oranges, and browns; and finally, anthocyanins, which produce reds and purples. Plants are chock-full of chlorophyll in spring and summer, capturing the sun’s rays and turning them into their own food. The levels of this pigment are so high, in fact, that it masks the other pigments in the leaves. As fall approaches, this process slows down and eventually stops altogether. This is when the other pigments, carotenoids and anthocyanins, become visible.
Other factors effecting autumn color are temperature and moisture. Since these can vary greatly from year to year, autumn tends to be like snowflakes in that no two are ever alike. Warm and sunny days followed by cool nights bring about the most vibrant colors. Carotenoids are always present in leaves and respond well to these conditions, so the yellows and golds seen in autumn are fairly consistent. Anthocyanins respond to bright sunlight in the beginning of the fall season. This encourages sugar production in the leaves which in turn fosters the anthocyanin pigment and results in brilliant displays of scarlets and reds.
Furthermore, different trees display the same colors year after year due to their genetics. Oaks turn red, brown, or a russet color. Scarlet oak and northern red oak turn brilliant shades of red. Look for them locally along with willow oak, pin oak, and swamp white oak. We live in the pine-oak forest community, and play host to numerous species of oaks.
Hickories turn a golden bronze. They also drop their bounty this time of year.
Dogwoods tend to be a purplish red. They also have reddish berries that are quickly devoured by our bird community.
Beeches turn a light tan color and actually hold onto their leaves the longest. You will most assuredly see their leaves flitting in the wind during the late autumn and winter months. Just drive up and down Route 1 and look into the adjacent woodlands; standing next to the glistening hollies you will find the beeches.
Red maples are a brilliant scarlet in fall. Sugar maples—most famous in New England for their sugary sap—are hues of oranges and reds. Norway maples, an invasive in our region, turn a yellow color.
Aspens and birches turn a clear yellow and poplars are more golden. I find these to be the least constant year after year; their colors depend a lot on temperature and moisture availability.
Fothergilla is one of my favorites and it turns stunning shades of orange at this time of year. Since this is a shrub, it provides a lot of color at ground level.
Bark also contributes to the colors of fall. Red twig dogwood pop in the landscape with their bright red stems (there is a yellow variety, too). River birch trees have a wonderful peeling bark that shows off its pinkish hues. Some Japanese maples also have brilliant colored stems like those of the coral bark Japanese maple.
The sense of smell is also awakened in autumn. Some leaves like those of the katsura give off a sweet smell of warm sugar when walked upon. I fondly remember taking a stroll on my college campus and slightly crushing them underfoot. It smelled like someone was baking cookies—no joke. Witch hazel actually blooms in autumn right after its clear, yellow leaves drop; the blooms’ light, spicy fragrance is a marvelous surprise in the autumn garden.
These ingredients of color and scent, coupled with the time for harvesting our incredible local crops—it’s no wonder that this is my favorite season. So, as I sit here drenched in 97% humidity, sticking to my leather recliner and eating ice cream like it’s my job, I am imagining enjoying a chilly evening in front of a fire pit, sipping my hot cider, and eating some apple dumplings. The colors and scents of autumn last for only a short while, but during those spectacular weeks, nature gives us a show we won’t soon forget. ▼
Eric W. Wahl, RLA is a landscape architect at Element Design Group and president of the Delaware Native Plant Society.
Image by Greg Shield on Unsplash.