As the days get shorter and the air becomes cooler, you can feel a noticeable change in the world. The leaves, dressed in shades of gold, amber, and crimson, slowly fall to the ground like a beautiful painting created by nature itself. Have you ever wondered why leaves change color in the fall? It's like a magical makeover that trees put on, and it's all thanks to some pretty cool science. Let's learn why it happens, and where at the Arboretum you can see these beautiful colors for yourself!
Most of the spectacular colors of autumn have actually been in the leaves all summer, but they were "covered up" by the dominant green of the chlorophyl. As weather cools, and shorter days settle in, the chlorophyl begins to break down, revealing new and varied color pigments. The brightest colors are seen when late summer is dry, and autumn has bright sunny days and cool nights.
First up, we have a superstar named chlorophyll. It's the green pigment that works hard during spring and summer, helping trees make food through a process called photosynthesis. Think of it like a tree's kitchen, where sunlight, water, and carbon dioxide combine to create yummy energy for the tree. That's why leaves look so green!
As days get shorter and temperatures drop, trees get a signal that it's time to gear down for winter. This is when chlorophyll takes a break from its busy schedule. As it steps off the stage, other pigments get their chance to shine.
Next in line are the carotenoids, which are like the artists behind those warm yellow and orange hues. They're always there in the leaves, but they're a bit shy when chlorophyll is around. When chlorophyll steps back, carotenoids finally get their time in the spotlight, painting the leaves with cozy autumn colors.
Now, let's give it up for the anthocyanins! These are the rockstars responsible for the fiery reds and purples that make leaves stand out. Unlike chlorophyll and carotenoids, anthocyanins aren't always hanging out in leaves. They're like the surprise guests that show up when the party gets cool. Their presence depends on things like temperature and light, adding an extra layer of excitement to the show.
Last, but certainly not least, we have Xanthophylls! They are another group of pigments that play a significant role in the autumn color show. These pigments, like carotenoids, are always present in leaves but are often masked by the dominant green of chlorophyll. Xanthophylls are responsible for the more subdued yellow hues that we see in leaves during the fall.
So, next time you're out and about in the crisp autumn air, take a moment to appreciate the incredible science behind the changing leaves. It's like nature's way of saying, "Hey, check out what I can do!" The colors are not just beautiful, but also a reminder of the amazing processes happening in the world around us. Now that we've learned the why, let's talk about where at the Arboretum you can find these beautiful colors!
Starting in late October through early November, the Larch Collection puts on a spectacular display of vibrant gold. These unique trees are deciduous conifers, meaning they lose and replace their needles annually much like how most of our broadleaved trees do. This collection contains European and Japanese larch, as well as our native tamarack.
Head out to our Maple Collection to see some of the most vibrant and diverse color displays out of any of our trees here at the Arboretum. Ranging from vibrant crimson associated with the red maple to warm oranges and golds found in the sugar and sentry maple. Many of the trees in this collection will start changing into their fall colors in late September through early October.
Looking for a pop or red in the understory? The Food and Forest Collection is home to many different cultivars of chokeberry, a North American native shrub that is considered the best replacement for the invasive burning bush. These stunning shrubs are also a good place to find birds in the late season as they hang on to an abundance of berries into the winter months.
Sporting a unique color combination of purple and gold in the fall the trees in the Ash Collections often begin turning in late September although there is a great deal of variation between species and locations. Leaves rarely stick around long on the trees and begin to drop shortly after turning color.
The Witch Hazel, one of our only fall-flowering shrubs can be found in the DAR Garden. Starting in mid-October through early November, this unique plant will begin producing an abundance of little yellow flowers. Additionally, visitors of this garden should be sure to check out the dawn redwood located on the edge of the collection, which will be decked out in vibrant yellow starting in late October.
An extra pop of fall color can be found in abundance among our many field habitats here at the Arboretum as a variety of wild asters come into bloom. These impressive native flowers put out a diverse display of vibrant purples, pinks, lavenders and white that contrast beautifully against the golds and browns of the fields.
Whether you're a seasoned admirer of the season or a newcomer eager to experience its allure, there's something here for everyone.
By: Bethany Drouin & Lauren Kircheis
