Red, yellow, orange, and even purple . . . You KNOW it's fall when the trees are a-blaze!
What to look for:

This is a
Sugar Maple Leaf.

Find a tree with leaves shaped like the one shown here.

Tell us when the whole tree is colored orange, red, or yellow.

There are five kinds of maple trees in Minnesota: sugar, red, silver, black, and mountain maple. All maples have palmately-veined leaves (shaped like your hand with your fingers and thumb spread out) and opposite branching. You can be sure the leaf from your tree is a Sugar Maple by checking its shape on this on-line tree key.

Watch in your neighborhood and around school. If you think you are the first person to see this event, ask your teacher to submit your name to the Wolf Ridge website (see table below.)

Where do Sugar Maples grow?
Sugar maples grow in most of the Fall Happenings forested areas. They are common in the temperate deciduous forests, but occur only occasionally in the coniferous forests of the north near the Canadian border.

Some of you might need to watch Red Maples instead - just let us know in the comments section when you report the event.
Why do leaves turn color?

Winter feel like a cold desert to a deciduous tree.

During the warm spring and summer, water travels through the tree in thin, stiff, straw-shaped tubes called xylem (the same stuff that we think of as wood - one or a few xylem cells might give you a sliver). Water is absorbed underground in the smallest roots, travels through the trunk and branches, and goes all the way up to the leaves.

We can't drink frozen water (ice), and neither can a tree. Winter feels like a cold, dry desert to trees. Since the flat, thin leaves of deciduous trees would dry out in winter, they can't stay alive. (Evergreens have special "needle shaped" leaves that don't dry out as much in winter. They can keep their leaves all year long.)

So, what's a deciduous tree to do? Loose those leaves! Before the tree's leaves fall off, they change color. Look below to see where the colors come from.
What makes the colors?
Chlorohyll
Carotenoids
Anthocyanin
(acid soil)
Anthocyanin
+ Carotenoids
Anthocyanin
(basic soil)
Tannins

The bright red, orange, and yellow colors we see in fall come in several ways:

All leaves get their green color from a pigment called chlorophyll. Chlorophyll is incredible stuff. It makes life possible on this planet by helping plants make every speck of food that ends up in every living creature, including us humans! Using chlorophyll to capture sunlight, plants combine water and carbon dioxide and change it into the sugar that eventually feeds us all.

The thing is that leaves can only make this amazing green-colored chlorophyll when conditions are just right. And they need to make more each day because the chlorophyll is constantly breaking down and needs to be replaced. In fall, the leaves are no longer making enough chlorophyll to keep up, and eventually there is no more green color to be seen. That means we get to see all the other colors behind the green!
Cool Facts
Individual trees of the same species will be different colors, just like people. This is because each tree has slightly different genes.
Night Temperatures - cool fall nights and sunny days make
brighter reds in maples
Red and Purple Colored Leaves. While yellows are revealed when the green fades , reds and purples (orange leaves are a mix of red and yellow) are actually MADE in the leaf in fall. Sugar trapped in the leaf reacts with other chemicals to make the red or purple pigment anthocyanin.
Spring weather can affect fall leaf color. If it doesn't rain much in spring, fall colors will probably be duller.

Think About It!
  1. Why do you think the trees turn color early in the fall in some years and late in other years?
Explore the Web
Young Naturalists article in the Minnesota Volunteer.
Kid-friendly general site from the Wisconsin DNR.
Learn more about trees in these Wolf Ridge classes:
You can take the Trees and Keys class at Wolf Ridge. During Trees and Keys class, you will travel through the trees and keys course, visit trees and see how many you can correctly identify. At the end of class, you will receive a tropical forest tree seed to plant to remind you of the value of maintaining biodiversity.
Hike away from the main Wolf Ridge campus through the woods and across the boardwalks to our Forestry Building outpost. You'll pack a lunch and be gone for the day. During the Forest Ecology class, you'll hike through a variety of managed forests, getting a chance to do some forest management along the way, beginning with a try at an old-time cross cut saw, and ending by taking on the role of a forest, wildlife, recreation, or water management specialist.
Explore the world of plants! Learn about how plants live and grow, why they are so different, and how they are alike. How do plants and animals help each other? Depending on the season, you might also make foods, drinks, perfumes, or dyes from the plants you find. More about our Plant Study class.
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