How Do Plants Get Taller Without Flopping Over

Leaf veins Have you ever wondered how trees get so tall without flopping over? Or how water from the ground gets all the way to the tree’s top? Well, it’s a fascinating story that begins with tiny “pipes,” or “straws.” There is a plumbing system that starts at the roots and moves up the stems and into the leaves, AND another plumbing system that takes the food each leaf makes and shares it with all the other parts of the plant. You’d think we could never see these pipes, but we can find evidence three ways: in leaf veins, in “tree rounds,” AND even in twigs. Let’s see if you can find proof of their existence. Your Quest! Come to an understanding of a few special science terms. Learn about a plant stem’s job, a plant’s plumbing (vascular system), and the parts of a twig. After that you will use a “tree round” to find a tree’s age. Later you will identify four native trees from photographs of their bare twigs. Then, using a hand lens, you will go outside searching for these same four deciduous trees (leafless in winter) and the proof of their “plumbing.” Finally, you will learn how to create a dragonfly using twigs and winged maple seeds (samaras). FIRST AN EXPERIMENT: Here are the directions 1. Review the glossary. 2. Look over the diagram of xylem and phloem. 3. Collect your materials for the experiment. 4. Make a hypothesis. 5. Conduct the experiment. 6. Review your results 7. Read the background information to see the science behind the results. Xylem (blue) and Phloem (orange) Glossary: • System: a group of two or more structures working together to perform a job—for your quest structures would be tiny plant parts • • • Xylem (zie-lem): a system of structures that together act like a tiny pipe or straw to move water and minerals up from the roots through stems to the buds and leaves Phloem (flow-em): a system of structures that together act like a tiny pipe to move sugars that leaves make to all other parts of the plant Adhesion: when water particles stick to other things like xylem and phloem pipes • Cohesion: when water particles stick to other water particles Materials: • Two drinking glasses or jars able to hold up celery • Water • Red or blue food color • 2 Stalks of celery with leaves (white flower optional) • Knife (with parent help) or scissors Steps: 1. Fill one jar with 1-2 inches of water. Leave one empty. 2. Add about 8 drops of food color into the water. Stir. 3. Cut ½ inch off the non-leaf end of each piece of celery. 4. Place one cut end into the jar with colored water the other in the empty jar. 5. Put the jar in a warm place (kitchen is good) and leave it alone overnight or longer. 6. Come back and look at the celery. 7. Slice about 1/4 inch off the bottom of the one in water and look at the cut end. 8. Ask an adult to scrape a little off the celery rib to view the veins vertically. What do you notice about the veins, the leaves, and the celery without water? Why did all of this happen? Leaves appear darker because of the food color in their veins. Background: Have you ever eaten celery and got “strings” caught in your teeth? Well, those strings are the pipe-like xylem and phloem. The strings stuck in your teeth, and this experiment have proven that plants have plumbing. In the celery experiment, colored water went up the pipes and turned them a color, while the celery in the other jar wilted because it had no water to move up its pipes. Plant stems have two main jobs: 1) move fluids through paired up bundles of xylem and phloem pipes, and 2) to support the plant so it can hold up leaves up to the sunlight. How does water move up a plant? When plants are full of water, like the celery in our experiment, some of the extra water leaves the plant through little holes in the leaves called stomata. As water particles move into the air, they pull on the water particles left in xylem in the leaf, which pull on the particles in xylem in the stem, which pull on the particles in xylem in the root. Because of cohesion, it’s like a big chain of water from root to stem to leaf and into the air. The same thing happened in our celery experiment, except water particles from the glass with colored water dragged the food coloring with them. BUT the food coloring didn’t evaporate into the air. It stayed in the celery leaf. Huge trees move water and minerals in the exact same way, but they move lots more water. Xylem moves water one way - up. Phloem, however, works a little differently. A leaf sends the sugars it makes in different directions depending on the location of the leaf on a branch. Leaves higher on a branch send sugars up to the tip. Lower leaves send sugars down to the roots, and leaves in the middle will send sugars in both directions. So, what make a stem so strong that it can hold up the entire plant? Some stems are green, flexible, and live for only one season, like celery. Heartwood = dead xylem Other stems are woody and live through several season, even years, but both these types of stems have the same structures. Tree trunks are just huge plant stems that support many branches, leaves, flowers, and fruit. Their trunks must be extremely strong to hold everything up. So, what makes them so strong? Does this have anything to do with their pipes moving water and sugar? Yes! Although phloem is strong, xylem is pretty strong and stiff by itself because its tubes contain fibers called lignin (lig-nin) and cellulose (cel-lu-lose), which helps plants become stiffer and stronger. And guess what? Together, lignin and cellulose forms wood. In fact, the center part of a tree is made of nonliving xylem tubes called heartwood and although not living, heartwood remains very strong. If we had a microscope we would be able to see that the xylem and phloem bundles in trees form a ring inside the stem. Imagine blue straws glued vertically to all the blue dots in the model on the left. Then doing the same with brown straws glued to the brown phloem dots. This model should give you a good visual image of what makes tree rings. In the model, though, the xylem/phloem ring is a HUGE version of the rings you see on a tree slice. Without a microscope we cannot see xylem/phloem bundles in a tree slice. We can only see the rings. Xylem Phloem If you’ve ever seen a tree stump, you’ve noticed lots of rings. These rings include thousands of xylem/phloem bundles and can tell us how old the tree is. They can also tell a story about climate and changes in climate throughout the tree’s life. Lightcolored rings tell of rainier times with lots of growth in spring, and dark rings tell us of times with less water and higher temperatures in late summer and fall. A light ring plus a dark ring equals one year. If the light and dark rings together are thin, it usually means the tree grew in dry, stressful times; and wider rings mean wetter, favorable times. Since you now know that tree rings tell the age of a tree, how old is the tree in the box above? Remember one year means one light ring + one dark ring. Hint: start in the center and count out. Answer is on bottom of the next page. Let’s investigate the parts of a twig and prove once again that trees have plumbing. Directions: ▪ ▪ ▪ ▪ ▪ ▪ ▪ ▪ Review the twig terms and diagram on the next page, especially terms circled in yellow. Read the descriptions of four different trees’ twigs in winter while referring to the diagram. Look over the photographs of four trees’ twigs. Match the descriptions to the photographs. Check the box near the pictures with the tree name that matches the description. Check your answers on the dragonfly page. Review the tree’s overall description before you go outside searching for trees. After you have practiced with pictures GO OUTSIDE with a hand lens and find the four trees and their twig parts. Actually, look at any tree with bare branches and HAVE FUN! Vascular Bundle Scars: A small dot on a leaf scar where bundles of xylem and phloem were once connected to a leaf. BUD: a small growth at the tip or on the side of a stem that later develops into a flower, leaf, or branch Terminal Bud scale scars from last year’s terminal bud; shows age of twig Year 1 The tree ring is 19 years old. - 1. Compare the photo of the twig to the diagram. 2. Decide if the buds are opposite (side-by-side), or alternate (like steps). See below. 3. Find the leaf scar. 4. Find the vascular bundle scars, where leaf veins connected to the branch. 5. Can you see lenticles? 6. Determine how old the twig is. 7. Can you identify the tree yet? Steps to learn parts of a twig: Twig Description Vine maple (Acer circinatum) ▪ Young bark on twigs is shiny, deep red or pink and sometimes lime-green on one side. ▪ There are many small, pale lenticels. ▪ Buds are opposite, a deep burgundy and about 1/8” long, but the terminal bud is longer. ▪ Terminal buds usually appear in pairs, but sometimes in threes. ▪ Fine hairs often emerge from the base of the bud. ▪ Leaf scars are very narrow, hard to find, but contain THREE bundle scars, if you can find them. ▪ Some fine hairs fringe the leaf scars. ▪ ▪ ▪ ▪ ▪ ▪ ▪ ▪ ▪ ▪ ▪ ▪ ▪ ▪ ▪ ▪ ▪ ▪ ▪ Big leaf maple (Acer macrophyllum) Winter twigs and new growth are shiny, deep red. There are many pale and bumpy lenticels. Bud scale scars are highly visible. Buds are opposite and ½-inch long with rounded tips. Buds get bigger as you move up the stem; terminal buds are very noticeable. Lateral buds are very small, even undeveloped looking. Bud scales are thick, deep-burgundy, and overlap. Leaf scars are U-shaped and light brown. There are SEVEN bundle scars but often you can only see five. Red alder (Alnus rubra) Young bark is reddish green with many lenticels. Vertical ridges make the stem look and feel square. Buds attach to the branch by a short stalk. Buds are 5/8-inch long and covered with light green/pink to red scales. Buds are oval shaped and rounded at the tip. Buds are often sticky. Leaf scars are usually kidney shaped. There are THREE bundle scars. The center one sticks out more and has two or more parts to it. Sometimes small cones hang on into winter and cluster near the ends of twigs. Sometimes catkins are noticeable in early winter. Black cottonwood (Populus balsamifera ssp. trichorpa) ▪ The many bud-scale scars give the twig a bumpy or warty appearance. ▪ New growth looks like it is coming out of a glass. ▪ Buds are alternate, ½ to 1-inch long, curved, stiff and sharply pointed at the tip. ▪ Buds are reddish-brown to green. ▪ Bud scales are layered and sticky. ▪ It has large, white, visible lenticels. ▪ Leaf scars are small, roundish triangles, and contain THREE bundle scars—the center one is larger than the other two. Overall Tree Description for the Search Vine maple (Acer circinatum) This is a small tree up to 30 feet tall. It prefers shady places but can be found in the sun. It has a rounded crown (general shape at the top). The trunk is sometimes leaning or might have many trunks. When living in very shady places, the branches often twist and crawl near the ground like a vine. ▪ Bark on older trees is gray and pretty smooth. ▪ Winged seeds (samaras) can be found under trees. ▪ It can be found with the other three trees you’re searching for. ▪ ▪ ▪ ▪ ▪ Big leaf maple (Acer macrophyllum) ▪ It is one of the most common deciduous trees around here. ▪ It can reach up to 100 feet tall with a spreading crown up to 50 feet across. ▪ Older bark on trunk is light brown to gray with vertical grooves. ▪ Young bark can be entirely smooth. ▪ It does well in most habitats—wet or dry, sun or shade. ▪ Winged seeds (samaras) can be found under trees. ▪ It can be found among the other three trees. ▪ ▪ ▪ ▪ ▪ ▪ ▪ ▪ Red alder (Alnus rubra) It can grow 50 to 100 feet tall. The crown (shape of the top) is cone shaped. The trunk is quite straight. Older tree bark is smooth, and silvery gray, and often covered with flat, white patches of lichen, an interesting organism that is part algae and fungus. Mature trees have cones and catkins. They live in damp places. Many can be found where the ground has been disturbed: bulldozed, fire, landslides…. It can be found among the other three trees. Black cottonwood (Populus balsamifera ssp. trichorpa) ▪ This is a large tree 100 to 200 feet tall with a trunk diameter of 3 to 6 feet across. ▪ Older trees have bark that is thick, rough, and deeply grooved. ▪ Younger tree bark is smooth and green turning to gray. ▪ Twigs often droop down from larger branches curving at the end like a hook. ▪ It grows in wet areas near creeks, rivers, lakes, and ponds. ▪ It can be found among the other three trees. Big leaf maple Black cottonwood Red alder Vine maple Big leaf maple Black cottonwood Red alder Vine maple Stalk Big leaf maple Black cottonwood Red alder Vine maple Partnership Big leaf maple Black cottonwood Red alder Vine maple Answers are on the bottom of the next page. Do you know what predator begins life underwater, goes through an amazing metamorphosis, and flies away searching for more prey? Dragonflies! Do you know what the State insect of Washington is? It’s the green darner dragonfly (Anax junius). It became Washington's official state insect after a group of students at Crestwood Elementary School in Kent brought the idea to the Legislature. So, to honor this insect, which is a friend to gardeners and mosquito haters everywhere, we will create its likeness in a sculpture made entirely of natural materials. Materials: ▪ Twigs (Ones with “opposite” buds make great “eyes.”) ▪ Several maple samaras (winged seeds) 4 for each dragonfly ▪ Scissors ▪ Glue (white glue dries clear) ▪ Waxed or parchment paper Directions: See numbered pictures that match steps. 1. Gather supplies. 2. Put waxed or parchment paper on a table. 3. Match four similar sized and shaped samaras for wings. 4. Cut off the seed part of the samara for easier gluing. 5. Place two “wings” side by side with edges overlapped slightly. 6. On the waxed/parchment paper, glue in between the overlapped parts of the “wings” and let glue the dry well. 7. Once dry, move the wings about ¼-inch apart on the waxed/parchment paper, so they look like dragonfly wings. 8. Add a generous dollop of glue to the place where you joined them together. 9. Quickly place your twig right on top of the wings, leaving a bit of twig showing above the wings. 10. Place a little weight on the twig until the glue dries. Resting part of the scissors on the twig works well. 11. When dry, GENTLY pull the dragonfly away from the waxed/parchment paper and turn it over. 12. Nice job! You’re done! You may decorate your creation or leave it natural. 4 5-6, 8 9 1 11 Answers: Tree #1 is black cottonwood. Tree #2 is vine maple. Tree #3 is red alder. Tree #4 is big leaf maple. Nonfiction Books Haiku (5-7-5) Xylem moves upwards Phloem moves down and around An awesome system NGSS (Next Generation Science Standards) LS1: Plants have both internal and external structures that serve various functions in growth and survival. Plants acquire their material for growth chiefly from air, water, and sunlight. LS2: Matter cycles between the air and soil. Plants obtain gases and water from the environment and release matter (gas, or liquid) back into the environment. When the environment changes in ways that affect a place’s physical characteristics, temperature or availability of resources, some organisms may survive, others survive less well, and some cannot survive at all. PS1: Matter can be subdivided into particles that are too small to see. Gases are too small to see PS2: Objects in contact exert forces on each other. (water’s cohesive & adhesive properties) PS3: Energy is present whenever there are moving objects/matter. ES2: Rainfall affects the types of living things found in a region. Scientists record patterns of weather across different times and areas so that they can make predictions about what kind of weather might happen next. Climate describes a range of an area’s typical weather conditions over years. SEP: Develop and use models. Botany: Plants, Cells and Photosynthesis by April Chloe Terrazas Can you Hear the Trees Talking? by Peter Wohlleben Cooking with Sunshine: How Plants Make Food by Ellen Lawrence DK Eyewitness Books: Plant by David Burnie Experiment with Parts of a Plant by Nadia Higgins Exploring Stems by Kristin Sterling Flowers, Leaves, and Other plant Parts by Jacob Batchelor From Seed to Plant by Gail Gibbons How Plants Grow by Dona Herweck Rice Inside Plants: Invisible Worlds by Barbara Taylor Nature Records Earth’s History by Baby Professor Peeking at Plants with A Scientist by Patricia J. Murphy Plant Parts Smarts by Eric Braun Plant Plumbing by Susan Jane Blackaby Charlene Delage Plant Secrets by Emily Goodman Plant Stems & Roots by David M. Schwartz Plants by Rachel Lynette Plants by Rebecca Rissman Roots, Stems, Leaves and Flowers by Ruth Owen Seeds, Stems, and Stamens by Susan E. Goodman Stems by Vijaya Khisty Bodach Stems by Charlotte Guillain Stems by John Farndon Stems by Marissa Kirkman Tell Me, Tree by Gail Gibbons The Magic and Mystery of Trees by Jen Green The Magic School Bus Plants Seeds by Joanna Cole The Mystery of the Tree Rings by Mark Meirerhenry The Tree Book for Kids and Their Grown-Ups by Gina Ingoglia The Tree Rings’ Tale by John Fleck Tree Story: The History of the World Written in Rings by Valerie Trouet Trees All Around by Pamela Hickman Trees, Leaves, Flowers, and Seeds by DK Smithsonian What Are Stems by Molly Aloian