Have the leaves come off the trees in your area yet? If so, it’s a great time to take your children out and try to put the leaves back on the trees.
Of course, not literally. Instead, find leaves on the ground and try to figure out which tree they came from.
All you need is a good tree identification guide that shows both leaf shape and bark patterns. First identify the leaf by it's shape and then find the tree by it's bark pattern and general shape.
You might start with some trees you know just to see how it works. Remember that leaves blow around. Look for nuts and seeds to match with the trees that produced them, as well. Children really enjoy this if you treat it like a game.
During a quiet moment, have your children take a good look at the trees. Once the trees have lost their leaves, other aspects of their structure are revealed. The texture of the bark, the shape of the branches, even the leaf scars on the twigs. Compare different trees. Close your eyes and feel the bark. Listen. Smell the wood. Do trees smell differently?
You can also take some paper and crayons along and let your child make a few bark rubbings. Place the paper on the trunk of a tree and rub the crayon over the surface. The bumps and grooves in the bark will be revealed. Hold the paper as firmly as possible for the best results. You can also trace the outline of dried leaves from the same tree.
If you don’t have one, here are some examples of tree identification guides. Have fun!
Trees, Leaves & Bark (Take-Along Guide) (Paperback) by Diane Burns
Winter Tree Finder by May T. Watts and Tom Watts
Winter Botany by William Trelease. A cool book on a cool topic!
Trees of North America: A Guide to Field Identification, Revised and Updated by C. Frank Brockman. Rebecca Marrilees
Eastern Trees (Peterson Field Guides) by George A. Petrides, Roger Tory Peterson (Illustrator, Series Editor)
Coming from a place where the leaves on the trees turned brilliant colors each fall, I guess having the calendar say that it is fall made me yearn for some color. Is there any better way to get children outside than to go check if any tree leaves are turning their autumn colors yet?
During your trip you or your children may have some questions about the whys and wherefores of leaves turning yellows, oranges, reds, and maroons.
Most trees have green leaves during the growing season. Look closely, however, and you will notice not all the leaves on a tree will be the same color. New leaves will be a lighter, brighter green. Older leaves will be dark green. Leaves that are about to fall off are yellow.
How do scientists study the colors in plants? One way is to perform a simple color separation or “chromatography.” The materials that reflect or absorb certain colors when subjected to light are called pigments. In the following test, we are looking for the pigments found in growing plant leaves.
The chromatography does require some time, at least an hour, so prepare your children in advance. It also requires rubbing alcohol. I tried to use water as a solvent instead and it just didn’t work. Note: If you are working with small children around, make sure they won’t try to taste the mixture, because of the rubbing alcohol. Read and follow the warnings on the label carefully.
You will need:
A spinach leaf per child (spinach is full of pigments)
Small clean containers, like a yogurt cups or jars (paper leaks) for one per child
Tool to chop the spinach leaves (requires adult supervision)
Rubbing alcohol (adult should pour)
Stirring utensil that will fit in containers
Coffee filter cut into about ¾-inch-wide strips that will fit into the container from top to bottom, one per container
Chop up the spinach leaves into tiny pieces. Put the chopped bits into the bottom of the containers. They should cover the bottom in a layer, up to ¼-inch deep. An adult should pour in just enough rubbing alcohol to cover the leaf bits. Stir a few seconds. Slide the coffee filter strip into the container, so that the bottom touches the alcohol/leaf mixture. Rest it against the side. Now wait for about an hour.
The alcohol should slowly move up dry part of the coffee filter, carrying the pigments as it goes. The heavier pigments will travel more slowly, the lightest most quickly. Once the wet alcohol front nears the top of the strip of coffee filter, remove it. Check the colors. Lay it on a piece of paper towel or paper and let it dry a bit. Often the colors of the pigments will show more intensely once the alcohol has evaporated.
Your coffee filter might look like this:
The green bands at the bottom are chlorophyll pigments. The plant uses chlorophyll to convert the sun’s energy into food. If you look closely, there are two bands of green, with some yellow. Those are the two chlorophyll pigments, named chlorophyll a, and chlorophyll b.
Just above the green is an intense yellow band. The yellow is a group of pigments called xanthophylls. Xanthophylls make corn yellow. When chickens eat plants with xanthophylls, they can use it in their eggs to make the yolk yellow.
At the very top, is a thin orange band. Those pigments are carotenes, named for the first plant tissue they were isolated from, carrot roots. Carotenes are also found in pumpkins and squash.
Now compare the colors in the growing spinach leaf to those of the autumn leaf. What colors are the same? What colors are missing in the leaves? What colors are in the leaves but not in the spinach?
First I notice very little green in the autumn leaves. The chlorophyll pigments break down in the fall leaves. I do see the oranges and yellows. The carotenes and xanthophylls have been there all along in the growing leaf, but masked by the deep green. When the green disappears, we can see them.
I see another color, however, that wasn’t present before, an intense red. The red pigments are called anthocyanins, and are known for making flowers, and vegetables like beets, red or purple. It turns out that certain trees make a lot of anthocyanins in their leaves in the fall. It wasn’t there earlier in the year.
Right now scientists don’t know for sure why certain types of trees produce the anthocyanins. One suggestion is that the anthocyanins act like sunscreen to help protect the leaves while the last bits of nutrients are being moved out and down to the roots for storage over the winter. Another suggestion is that red trees are less visible to insects. Harmful insects may lay their eggs on trees in the winter, and may choose trees that are yellow over those that are red.
This weekend let’s go out and look for trees that are flowering. Whether you walk around the block or visit an arboretum, I bet you are going to discover more than you realize.
Certainly you are going to find trees with beautiful, colorful showy flowers like this desert willow. The buckeyes, horse chestnuts, tulip trees, catalpas, magnolias and fruit trees all have attractive flowers.
Do you have any ideas who might come to visit these flowers? In our desert willow we regularly have hummingbirds and carpenter bees. We’ve also noticed tiny birds, called verdins, poking around the flowers. The hummingbirds are collecting nectar, the bees collect pollen and nectar, and we aren’t sure what the verdins are after. They are probably drinking nectar, but they also catch insects. In the summer they love to eat the tomatoes in our garden. We forgive them though, because they are so tiny and cute.
You might have trouble spotting the flowers on certain trees, like this mesquite. They form catkins that don’t have petals, so may not look like flowers at all. Insects often pollinate trees with big, showy flowers; trees with small flowers may be wind pollinated.
Other tree flowers may be oddly shaped or peculiar compared to annual flowers. Check out the bell-shaped flowers from a bottle tree (Brachychiton populneum). From the side the flowers are whitish, and are hard to see. Facing the flower, however, the interior is dark red.
If you have studied flower parts, then tree flowers can offer some challenges. Sometimes trees will only have male flowers or only female flowers. Mulberries are examples of trees that have separate sexes. One tree will be female and produce fruit and seeds; another will be male and produce only pollen.
It's a good idea to jot down the date when you see trees in bloom. Recording the time of bloom gives information about phenology or dates of reoccurring natural phenomena. This information can then be used to study how plants respond to such things as weather and climate changes. Each tree has it’s own time to bloom and over the years you will see patterns.
If you can’t get outdoors, or you are interested in seeing more photographs of trees, check out the beauties at Julie Walton Shaver’s Tree Growers Diary. The Autumn in the Land Movie is particularly worthwhile if you love trees.