With so many vibrant colors beginning to show in our local forests and landscaping, have you ever wondered why tree leaves change color, or just what species turn what colors? Be prepared to learn a little about leaf chemical composition and tree identification.
Fall is an exciting time of year in our region due to the gorgeous landscapes that surround us. During summer and spring our tree leaves are varying shades of green, all due to chlorophyll being present in the leaves. Chlorophyll is the green pigment in leaves and is necessary in the leaves of plants in order to break down carbohydrates to be utilized as sugars in the plants for energy. However, chlorophyll production slows during the fall due to decreasing sunlight, allowing other pigments to show through such as anthocyanins and carotenoids.
Our own state tree, the tulip poplar, turns a pleasing yellow color, due to the amount of carotenoids present in the leaves. Carotenoids do not need sunlight to be produced, so they continue to be present even as the day length decreases. Other examples of yellow leafed tree species include the eastern redbud, sycamore, and hickories. You may have even noticed a brilliant yellow in a neighbors’ yard as a gingko tree changes color. The gingko is one of my favorite fall trees even though it is an exotic, not native to Tennessee.
Red and red-brown tree leaf color comes from the presence of anthocyanins in the leaves. Sassafras, sugar and red maples, and sourwood are examples of trees that produce vivid red fall foliage. Japanese maples are a common landscaping tree that also turns a pleasing red. Even poison ivy and Virginia creeper can become eye catching this time of year with their red leaves.
Orange foliage is derived from the presence of both carotenoids and anthocyanins in the leaves. Some oak and maple species turn bright oranges, while others are a more orange-brown. Though the yellows and reds are my personal favorites, their effect would be lost without the backdrop of the oranges and browns.
Now armed with just enough fall foliage information to be dangerous, it is time to get out and enjoy nature’s artistry. Never forget to plan for inclement weather, and always take a camera.