Dress Up A Twig
1. Show the class your Twigger of America card and tell them that you are an official member of this national organization. Explain that most people identify trees by the shapes of their leaves, but twiggers can identify trees without their leaves. Have the students guess what clues, other than leaves, can be used to identify and distinguish trees.
2. Explain to the class that a Twigger of America looks very carefully at the twigs of trees. Choose a volunteer to help you teach the class about the parts of a twig. Explain that you will dress up this volunteer as a twig.
3. Hold up a real twig. Ask the class what is at the end of the twig (a bud). Place a party hat (inside of which is a cutout leaf) on the volunteer twig's head to represent this bud. Explain that the bud at the tip of a twig is called the terminal bud. Ask the students what might be inside the bud (leaves or flowers). Have the volunteer look inside his or her bud to see if the students' guesses are correct. Stress that in all the winter buds on trees are next years' leaves or flowers. Be sure to point out that different types of trees have distinctively different buds. They may be different sizes, shapes, colors or have different smells.
4. Ask the students whether they see any other buds along the sides or side branches of a real twig. The side buds are called lateral buds. Explain that the volunteer's arms represent side branches and the lateral buds are often at the tips of these branches. Place matching party hats on the hands of the volunteer twig to represent lateral buds.
5. Tell the class that the arrangement of these lateral buds and branches is important in identifying trees. They can be aranged in one of two ways. Some trees have opposite branching. Have the volunteer stretch his or her branches (arms) out to the sides. Point out that one bud (hand) and branch (arm) is directly across from or opposite the other. Ask the class to imitate this type of branching pattern. Tell them that only a few types of trees have opposite branching. They are often called MAD HORSE trees; the letters in the word mad are the first letters of the names of these trees, and the horse represents a fourth. All these trees have opposite branching. Can the students guess what the trees are?
(The m stands for maple, the a for ash, and the d for a tree that barks, or dogwood; horse stands for horse chestnut.) As a joke, you might have the students keep their hands up in the air while you are explaining this and ask them if they would be mad, too, if they had to stand this way all day.
6. Next use the volunteer twig to demonstrate the second branching type, called lazy or alternate branching. Have the volunteer hold one arm up in the air and the other down to the side. Point out that in this type of branching, you do not find buds or branches across from one another, but rather alternating along either side of the stem. Most trees have alternate branching.
7. Explain that twigs have other parts that aid in identification. Along the twigs are leaf scars where last year's leaves were attached. Use tape to attach paper cutout leaf scars beneath each of the three buds on your volunteer twig. Point out that there may be marks, or bundle scars, on the leaf scar that form a pattern of tiny dots or lines. The bundle scars mark the place where veins ran from the leaf stem to the twig. Ask the students if they can see a design in the volunteer's leaf scar.
8. Another feature the students may see scattered over the surface of a twig are tiny holes or breaks in the bark. These are called lenticels and allow for air exchange. Place sticky dots all over the volunteer twig to represent lenticels.
9. Now your twig is complete. Review all the parts and the two types of branching patterns. Give your volunteer twig a round of applause.
a. Pass out freshly cut twigs to the class and have them identify the different parts. Have the students draw and label the parts of their twigs.
b. Place a few freshly cut twigs in water inside the classroom in late winter or early spring. This will force them to open or bloom indoors.