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30 Activities and Observations for Exploring the World of Trees and Forests
By Monica Russo, Kevin Byron
Chicago Review Press IncorporatedCopyright © 2016 Monica Russo
All rights reserved.
What Is a Tree?
Trees are almost everywhere. They are planted along streets and around playgrounds. They create pleasant, cool, shaded areas around homes in the summer. Trees provide food, shelter, and homes for birds and other wildlife. City parks and gardens are valued for their beautiful trees, and forests are enjoyed by hikers, naturalists, campers, and bird-watchers.
Is It a Tree or a Shrub?
Trees — and shrubs — are large plants with hard woody trunks or stems. Most have leafy branches or groups of leaves. Size is generally the best way to tell the difference. Shrubs usually grow less than 15 or 20 feet tall and often spread out close to the ground. A mature (fully grown) tree can grow tall and straight to a height well over 20 feet.
Most trees have a single main trunk that branches out into many smaller branches and twigs. But most shrubs have several woody stems rising right from the ground and then dividing into thinner branches. Your school, house, apartment, or nearby grocery store parking lot probably has several shrubs planted around it.
Here are some examples of shrubs:
* flowering lilac
* blueberry bushes
* honeysuckle bushes
* flowering forsythia
* others: hawthorn trees, witch hazels, and sumacs can often grow more than 15 feet tall, so they are described in field guides as small trees or large shrubs.
A single plant family can include both trees and shrubs — and even small woodland wildflowers!
It can be confusing to tell a tree from a shrub. Some trees don't grow tall because they are stunted by insect damage or poor growing conditions, such as drought. And many trees are pruned and trimmed so that they remain small. Even though they could become much taller, they are kept to the size of a shrub (less than 20 feet tall). Here are a few examples:
* Apple trees can grow more than 20 feet tall, but in orchards they are usually pruned and trimmed to keep them smaller to make it easy to harvest ripe apples from them.
* Rhododendrons can grow well over 20 feet high in the wild, but when planted in front of houses or public buildings they are kept trimmed to stay small.
* Hemlock trees growing naturally in the wild can grow 60 to 70 feet tall — with some huge specimens reaching more than 100 feet! But they are sometimes planted in rows near a building and trimmed and pruned to form a low hedge.
* A balsam fir can grow to be a large tree — usually 50 to 60 feet tall. But on a tree farm where Christmas trees are raised and grown, they are trimmed so they can fit inside a house for the holidays. Balsam firs in poor growing conditions may only grow a few feet tall.
Parts of a Tree
On the ground at the base of a tree, you can often see the top surface of large roots spreading away from the trunk. If you could dig up a large tree, you would find that the big roots divide into smaller roots, then into tiny rootlets, and finally into tinier roots called root hairs. You can sometimes see the entire root system of a tree when it has been blown down by a severe storm and the roots have been ripped out from the ground.
The trunk of most trees rises upward to spread out into large branches, then smaller branches, and then smaller and shorter twigs. The twigs support buds and leaves.
The leafy top of a mature, fully grown tree is called the crown. The tops of many trees, including maples, birches, oaks, and ash trees, are rounded. An American elm has branches and a crown that grow in a fan or fountain shape. A blue spruce, often planted near homes and buildings, has a triangular shape with a pointy top. Balsam fir trees have a triangular shape too (also called a pyramid shape).
Parts of a Leaf
The flat part of a leaf is called the blade. Some leaves have a very wide blade, like those of the American sycamore, which can be eight inches across. Other leaves are quite narrow. The leaf of a black willow tree is only about one-half inch wide. Pine leaves are called needles because they are long and very thin.
Leaves are attached to twigs by a stem called a petiole (PET-ee-ole). The petiole on the leaves of elms, chestnuts, birches, and oaks is fairly short. But the petiole on the leaf of a bigtooth aspen or on most maples is long. Look at the petiole on the leaf of any tree or shrub, and observe how long it is. Is the petiole shorter than the length of the leaf blade, or is it longer than the leaf? Bigtooth aspen, cottonwoods, and trembling aspen all have long, flat petioles, which cause the leaves to wiggle in a breeze.
Leaf Shapes and Designs
Leaves have many different shapes. Each species (type) of tree has its own leaf shape. There are many different species of maples and birch trees, and the leaves of each species have a distinct shape and size.
Leaves can be long and narrow, like those of willows. They can be oval, like those of cherry and plum trees. Some trees have leaves that come to a long point. The leaves of a white oak have rounded, fingerlike lobes. The leaves of sassafras trees can have three different shapes: a single oval, an oval with a "thumb" (a shape like a mitten), and a three-part leaf. All three shapes can be found on one sassafras tree!
The edge of a leaf also can be important in identification. Some leaves have a mostly smooth edge, like those of a southern magnolia. Others, like red maples and American chestnuts, have a toothed or serrated edge.
You may also notice that on some trees (and other plants) the leaves grow from the twigs opposite from each other. On other trees, the leaves are alternating (or staggered) along the branch. Once you start to look at the shape, design, and placement of different leaves, you will develop an eye for noticing details. This will help you to identify common trees, and to keep a lookout for anything different or unusual.
THE UNDERSIDE OF A LEAF
You need good light indoors for this activity, or a bright day outside.
* A few different leaves, picked from trees or shrubs
* Magnifying glass
1. Pick a few leaves from different trees or shrubs. (It doesn't matter if you can't identify them.)
2. Compare the upper side of the leaf with the underside. The underside is probably lighter in color.
3. Now look at the underside more closely with a magnifying glass. You will find that the veins are easier to see.
4. Look for a different texture than on the upper side. The underside may be smoother, or it may be rough, fuzzy, or hairy.
On the underside of hemlock leaves (which are short, flat "needles"), you can see white or silvery lines on each side of the central vein. These white lines are made up of special cells that surround tiny pores. You can also find white lines on the underside of balsam fir ("Christmas tree") needles.
The underside of a black oak leaf has tiny fuzzy hairs where a vein meets the central vein. It's a good way to tell a black oak from a red or scarlet oak. And the leaves of black cherry trees have rust-colored fuzz at the base of the leaf, just past the petiole.
Poison Sumac-Don't Touch!
Poison sumac is a shrub or small tree. Never touch a leaf of this plant! This is a very toxic plant, and even a slight touch will cause a skin rash that may need medical attention.
Collecting Leaves to Make Rubbings, to Press, and to Preserve
When you see an interesting tree, you might want to pick a leaf and preserve it. A fresh leaf can be preserved by pressing and drying it (which can take several days). Or you can quickly make a colorful crayon rubbing of a leaf — to decorate notepaper! This will make a copy of the leaf, so you will always be able to look at its shape and design.
You need oxygen to breathe. So do all other animals. Oxygen is a part of the air all around you, and a lot of it comes from plants — including trees! Plants need some oxygen too, but they depend on carbon dioxide (which animals exhale). So, while you breathe in oxygen and exhale carbon dioxide, plants use carbon dioxide and produce lots of oxygen!
Once you have collected several leaves that you like, you can easily press and dry them so they are preserved. Pressed leaves are often kept in scientific collections in museums and universities. Many are important historic specimens. They are lasting evidence that certain species were found growing in a particular place. Many specimens in scientific collections were pressed in the 1800s.
MAKE A CRAYON RUBBING OF AN INTERESTING LEAF
Try making crayon rubbings of different leaves in different colors. You can use your leaf rubbings as notepaper or to send a colorful message to a friend.
* A fresh leaf (any kind)
* Piece of thin cardboard (cardboard cut from a cereal box works best)
* White or light-colored paper
* Bright-colored crayons (like red, blue, or purple)
1. Place your leaf underside up on top of the cardboard. The underside usually has the strongest veins, which will show up best in a rubbing.
2. Put the white paper over it, and hold down the paper with one hand.
3. Rub the crayon over the petiole first, because it's easy to feel. Then rub all around the edge of the leaf. You'll feel (and see) the edge of the leaf as you color.
4. Go over the entire leaf with the crayon, pressing hard enough so that the shape of the leaf and the veins show up.
5. You might have to try a few different leaves — or crayon colors — before you are satisfied.
6. Use your rubbing as notepaper, a card, artwork, or letter paper.
PRESS LEAVES TO PRESERVE THEM
If you have found some leaves that have a shape you like, it's easy to press them and dry them so you can keep them preserved.
* Several sheets of newspaper
* 2 or 3 pieces stiff cardboard
* A few freshly picked leaves from trees (or shrubs)
* Something heavy, such as a few heavy books or a flat rock
1. Cut the newspaper pages into several smaller-size squares — about the size of a sheet of printer paper.
2. Place one piece of cardboard on a flat space, like your desk.
3. Lay two or three pieces of newspaper on the cardboard, and place a few of your leaves on it.
4. Cover the leaves with more newspaper. You might need several layers of newspaper to cover more leaves.
5. Put a final piece of newspaper over your last specimens, and add a piece of cardboard to the top. Put something heavy on top of it all — a few books or a rock.
6. Let the leaves dry and press for four or five days, and then turn them over. Let them dry and press again for a few more days.
How Many Leaves Are There on One Tree?
The total number of leaves on one tree is different from one species of tree to another, and from tree to tree. But a healthy, large, mature maple or oak tree can have about 200,000 leaves! In contrast to that, a small black cherry sapling, standing about four feet tall, has 172 leaves on it.
MAKE A LEAF SPECIMEN CARD
You can use one of your pressed leaves to make a specimen card that will last for many years.
* Plastic sandwich bag
* White paper
* Pressed dried leaf
* Colored pencils, pens, or crayons
1. Cut the cardboard to fit inside the sandwich bag. Cut it small enough so that the sealing-strip at the end of the bag can be folded over and taped.
2. Cut the white paper to the same size as the cardboard.
3. Carefully place your leaf in the center of the white paper. Stick a small piece of tape across the petiole to hold it in place.
4. Use a marker, pencil, or crayon to write your name, the date, and the place you found the leaf on the paper. Be careful to not touch the leaf — it might crack or crumble!
5. Carefully slide the white paper and leaf into the bag.
6. Slide the cardboard in the bag, under the leaf and white paper.
7. Gently smooth air out of the bag and press the seal at the end closed. Fold the sealed end around to the back and tape it.
Try making cards using different leaves. You can also draw a colorful border or margin on the white paper, around the leaf, or write a note on it, to give to a friend.
Across North America, there are more than 70 plant families that include trees — and more are found in Australia, Africa, Europe, China, and tropical areas around the world. While some of those families just include trees, smaller plants are also included — even wildflowers!
Families of Trees
Here are some of the most common tree family groups. It helps to remember that these are plant families, and the members of a family may include trees, wildflowers, shrubs, and even vines.
* Yew family. Yews have short evergreen needles, and a bright red berrylike cup surrounding each seed. Only two species of yews are found wild in North America. Species native (growing wild naturally) to other countries are grown for landscaping.
* Pine family. This includes the many species of pine, spruce, hemlock, and fir. These trees are usually called evergreens, because they look green throughout the year. But they do lose some of their needles every fall, and those get replaced in the spring with new growth.
The long, thin leaves of pine trees are called needles. The needles grow from the twigs in clusters called fascicles (FAS-i-kils). The needles on a pitch pine grow in fascicles of three. You can remember that the needles of an eastern white pine grow in fascicles of five by remembering that the word white has five letters, w-h-i-t-e!
Other species of pines have needles in fascicles of three and five also. Some species have short needles, while others have long needles. Sometimes it's hard to keep track of all the different types of pines! But it's fun to get a start in observing the details of pine trees.
Botanists (scientists who study plants) call trees in the pine family conifers, because they produce woody, scaled cones with seeds inside. Conifers have cones of different sizes: white pines have cones about six to eight inches long, but the eastern hemlock has much smaller cones — less than an inch long.
* Redwood family. The famous coast redwood of California and Oregon is a member of this family, along with the giant sequoia. Another member is the metasequoia, also called the dawn redwood. It is a native, wild tree in China but has been grown in nurseries and is sometimes planted around homes.
* Bald cypress family. This family includes many of the trees found in the swamps and marshes of Florida and the extreme southeastern United States.
* Cedar family. One member of this family, the northern white cedar, is also called arborvitae (ar-bor-VY-tee). It is native to the northeastern states and southeastern Canada.
COUNT A CLUSTER OF PINE NEEDLES
A pine tree can often be identified by the number of needles in a fascicle (cluster). It's easy to find a fascicle and then count the needles.
* Your sharp eyes
* Pine twig with fascicles (clusters) of needles on it. You might find a twig or branch on the ground if there has been a lot of wind. You can also count fascicles on a small seedling or sapling pine — even if it's only one or two feet tall!
1. Look at the twig and find a cluster (fascicle) of needles. The fascicle is securely attached to the twig. Count how many needles there are.
2. Count two more fascicles, just to be sure they all have the same number of needles. (Some may have been damaged by storms or by insects.)
Look for other pines in your area to see if they have fascicles with the same number. There are more than 20 species of pines in North America, so you might have more than one species of pine in your neighborhood.
Larches Are Different!
Larches are different than most other members of the pine family. Pines, hemlocks, firs, and spruces are evergreen all year long, but larches turn golden yellow in the autumn — and then all the needles fall off! Larches look very colorful in the fall, but they have bare branches all winter.
Larches are also called tamaracks or hackmatacks, names originally from the Algonquian Native Americans. Three species are found in North America. The most common one grows in the northeastern United States and across much of Canada. Larches can grow about 60 feet tall and have a pointed, triangular shape. The needles are short and grow in tight clusters, or even as single needles.
* Ginkgo family. These trees are native to China, where they grow wild, but they have been grown and raised in North America for a long time. Their unique, fan-shaped leaves are easy to identify. Fossil leaves of ginkgos have been found dating to the Triassic period — more than 100 million years ago!
Although the ginkgo is a native wild tree in China, it is grown and planted throughout most of North America. The leaves turn yellow-gold in the fall. The rounded fruit has a large seed inside.
* Palm family. This includes the coconut palm. Palms don't have branches like other trees, but have a fountain-shaped tuft of big fronds (large leaves) at the very top. There are more than 1,000 species in this family around the world in tropical areas. Along with trees, this family also includes vines and small shrubs.
* Willow family. Willows are widely known for their thin, drooping branches with narrow leaves. Black willows usually grow near rivers and ponds. Pussy willows are small, shrubby members of the family. Aspens, cotton-woods, and poplars are members with rounded leaves.
* Walnut family. This family includes walnut, hickory, and pecan trees.
* Laurel Family. This family includes the sassafras, a common tree throughout most of the eastern United States. Its range extends south into Florida and parts of Texas, and north to Michigan and southern Maine. Historically (about 100 years ago) sassafras wood was sometimes used to make furniture and fence posts in the southern states.
Excerpted from Treecology by Monica Russo, Kevin Byron. Copyright © 2016 Monica Russo. Excerpted by permission of Chicago Review Press Incorporated.
All rights reserved. No part of this excerpt may be reproduced or reprinted without permission in writing from the publisher.
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Table of Contents
1. What Is a Tree?,
2. Tree Families,
3. From the Ground Up,
4. Woodland Wildlife,
5. It's Dead ... No, It's Alive!,
6. It's Nuts! Food for Animals,
7. Out and About — Tree Treks,
8. People and Trees — and Forest Conservation,
Common and Scientific Names,