Plant Resource Page
The Case of the Tree Hit Man
Text taken from: Once Upon a Life Science Book © 2010 NSTA
The Big Question: How do water and food (sugars) move through a plant?
The assassin crept across the lawn in the dead of night. He worked quietly and efficiently. There were only a few hours until morning, and his work would need to be completed by the time the sun came up. He had been hired to kill one of Magnolia Springs' oldest and most respected residents: a 500-year-old oak tree.
The tree, named Inspiration Oak, had been growing since before the time of Christopher Columbus. It had survived the birth of the small town and the invention of the automobile. By 1990, it stood 65 feet tall, with a trunk that was almost 30 feet in diameter.
The owner of the land had decided to chop down the tree and build a gas station. The people of Magnolia Springs loved that tree, so county officials denied the permit for a gas station and collected money to buy the land instead. The owner's plans were foiled, and all because of that tree. But what if something happened to the tree? The owner got on the phone and called a hit man.
It's not easy to kill a big tree in a hurry. Chopping it down would take time and be noisy. Neighbors would be sure to notice. Poison might work, but it would take massive amounts of poison and could take years to finish the job. But the tree hit man had a plan because he know how trees were organized.
What the Hit Man Knew
Trees, like most plants, have three main parts roots, leaves, and stem. The roots hold the tree firmly in the ground so that even a strong wind will not knock it over. They grow deep into the soil and can stretch for hundreds of feet in all directions. As shown in Figure 1, the root network is as big as the trunk and the branches combined. Trees need this vast network of roots to absorb water and minerals for growth.
At the other end of a tree, you find the leaves. Leaves make food for the plant in a process called photosynthesis. The leaves get carbon dioxide from the air and water from the roots. Then they use energy from sunlight to convert the water and carbon dioxide into sugars.
The stem, or tree trunk, holds the leaves high in the air so they can get enough sunlight. The trunk also connects the roots and leaves. Inside the trunk, tubes carry water and minerals from the roots up to the leaves. Another set of tubes carries sugars from the leaves to the roots. These tubes are made of specialized plant cells that connect end to end. The cells that carry water up are called xylem. The cells that carry sugars down are called phloem. Together, the xylem and phloem are called the vascular tissue. Vascular tissue carries water and sugars throughout the roots, leaves, and stems.
In most plants, xylem and phloem are found in bundles throughout the stem. But in trees, the xylem grows in the center of the trunk and all of the phloem lie just below the bark on the outside.
Quick and Dirty Business
The hit man worked quickly to chisel into the tree. He made a perfect ring, six inches wide and six inches deep. WIth each cut, he removed the bark and the phloem layer. Thick, sticky liquid oozed from the wounds. Soon the tree had no way to get sugar from its leaves to its roots. It was only a matter of time until the root cells died of starvation.
In the morning, the townspeople were horrified. The brought in tree experts from around the country, who built an elaborate intensive care unit to try to reconnect the phloem tubes. But it was too late. The tree could not be saved. No charges were ever brought in the case of the tree hit man, but the town of Magnolia Springs came together in its effort to save the tree. They went through with their plans to but the land and build a park. It is a beautiful, quiet picnic spot that is marked with the giant stump of Inspiration Oak.
Pictures, Links, & Videos
Use the pictures, links, and videos on this side to help you learn more about bacteria. If you find other resources that we can use save them in Diigo and I'll add them to our list.
Basic Plant Structure
The Cycle of Photosynthesis and Respiration
Flower Parts and Story
Groups of Plants:
Tim and Moby on Photosynthesis and Respiration
Photosynthesis from a Seed's Perspective- Student YouTube
Figure 1: Tree Roots
Roots make up about half of the total size of a tree.
Figure 2: Stem Cross-Section
One way that Vascular Bundles can be Arranged in a Stem