MadSci Network: Botany

Re: Why did the plant I am feeding with coffee grow then wither and die?

Date: Sun Apr 18 10:07:17 1999
Posted By: Lynn Bry, MadSci Admin
Area of science: Botany
ID: 924443415.Bt

Hi again essence -

Based on the information you provided, I'm afraid that I can't interpret the results you describe. If you have time, I'd strongly recommend that you repeat your experiment, for a few reasons..

First - I'd recommend using at least three snapdragons and three cosmos. By only using one plant in each group, how do you know the plant wasn't sick to begin with, or damaged in some way? By expanding the numbers in your experimental group you're better able to distinguish true effects from your experiment versus events of chance that could produce the effect you saw (that the plant dies because it was sick or damaged as opposed to something in the coffee solution used to water it).

Second, you need control plants - plants that receive water instead of coffee. Again, I'd recommend using at least three plants each for each control group (meaning 6 snapdragons and 6 cosmos). The controls serve as your comparison group for any effects you see in the experimental group.

Third, keep a detailed log of how you perform the experiment. Record the state of the plants when you first bought them. Write down how often you will water them and with what solution of coffee. Each day note the time that you water the plants, as well as any changes in each one - browning at the tips of the leaves, formation of spots, yellowing of leaves, etc. You might also consider measuring if there is any change in height, or in the number of leaves the plants produce as you water them.

Then repeat your experiments. Be certain to treat the plants in the exact same way, varying only what you use to water them (pure water or coffee). They should receive the same amount of sunlight, be watered at the same time, and receive the same volume of water. You also need to make certain that your coffee solution is the same from day to day (i.e. add "two tablespoons of coffee to a quart of water," or whatever volumes you have decided to use). With this experimental setup, if all three snapdragons fed coffee die, but the controls survive, you will be in a better position to say that the coffee definitely caused the effect.

In the meantime, consider what you would do next, depending on the results of your experiments. If the plants die from coffee, what else could you try? For instance:

  1. Is the "strength" or concentration of the coffee solution important? What would happen if you repeated the same experiment using a weaker or stronger coffee solution?
  2. What specifically in the coffee is causing the effect?
Aside from caffeine, coffee contains many other chemicals. Many of these chemicals, including caffeine, can be purchased in pure forms. You can dicuss the possibility of ordering caffeine or other methylxanthines with your science teacher. Many science supply houses sell to K-12 schools.

Hope this helps..

Lynn Bry, Admin MadSci Network

Current Queue | Current Queue for Botany | Botany archives

Try the links in the MadSci Library for more information on Botany.

MadSci Home | Information | Search | Random Knowledge Generator | MadSci Archives | Mad Library | MAD Labs | MAD FAQs | Ask a ? | Join Us! | Help Support MadSci

MadSci Network,
© 1995-1999. All rights reserved.