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Avoid Misconceptions When Teaching About Plants

David R. Hershey

articlehighlights

Hundreds of plant misconceptions occur in the teaching literature.

  • Fifty misconceptions are identified in this article.
  • Some misconceptions are easier to identify because they are oversimplifications, overgeneralizations, or misidentifications.
  • Others are more difficult to identify because they are obsolete concepts and terms or flawed research.

August 2004

One plant misconception can potentially mislead thousands of teachers and students.
hersheyphoto2.jpg

Spanish moss ((Tillandsia usneoides), an epiphyte, on a Live Oak in Florida. Photo: Sheri Potter.

The teaching literature contains hundreds of errors or misconceptions about plants, but this problem has not received enough attention to prevent its negative impacts. A plant misconception in a single textbook, educational web site, science project book, teaching journal article, or curriculum guide can potentially mislead thousands of teachers and students. Teachers often cannot detect even glaring errors because “new teachers coming out of our universities and colleges are very poorly trained in basic botany.”1

Once learned, misinformation may be difficult to correct.

Many research studies have examined student misconceptions about plants.2-5 Not surprisingly, some misconceptions about plants also appear in the teaching literature, misleading students and teachers. Student misconceptions are difficult to correct even when teachers specifically attempt to correct them.3-5 Here I identify 50 plant misconceptions and five categories of misconceptions:

  • Oversimplifications
  • Overgeneralizations
  • Obsolete concepts and terms
  • Misidentifications
  • Flawed research

Oversimplifications

Oversimplification is prevalent at the precollege level.

Many misconceptions involve oversimplification of concepts, particularly at the precollege level. Such an “extreme of simplification” in plant teaching is not new.6 The following summary equation for plant photosynthesis is an oversimplification that contains several misconceptions:

             sunlight, chlorophyll

6 CO2 + 6 H2O ——————————————-> 6 O2 + C6H12O6 (glucose)

The explanation of photosynthesis is a particularly good example.
  • Chlorophyll alone is insufficient for plant photosynthesis. Many other enzymes and organic compounds are required. “Chloroplasts” is a better requirement.

  • Glucose is not the major photosynthetic product. There is virtually no free glucose produced in photosynthesis..7 The most common product is starch or sucrose, and students often test leaves for starch. Starch is approximated as (C6H10O5)n, where n is in the thousands.8

  • The six water molecules consumed per glucose molecule generated underestimates the water required. Much larger amounts are transpired to keep the stomata open. Without open stomata, photosynthesis is limited by lack of carbon dioxide. Submerged aquatic plants require large amounts of water for their aquatic environment.

  • Drawing a single arrow wrongly implies that photosynthesis occurs in one step. Many small arrows should be used.

  • Some of the energy captured in the light reactions of photosynthesis is used in the chloroplast to synthesize fatty acids and proteins.7 Thus, there are other types of “photosynthesis.”

  • The biology teaching literature contains much information on photosynthesis, yet it often has minimal discussion of mineral nutrient uptake by plants.9 To counter this problem, “mineral nutrients” should be added to the equation. Most essential mineral nutrients play a role in photosynthesis.

David R. Hershey, Ph.D., is a biology education consultant and author of Plant Biology Science Projects (1995, Wiley). He has published over three dozen teaching articles in journals such as Science Teacher, Science Activities, Plant Science Bulletin, American Biology Teacher, and BioScience. He answers botany questions for madsci.org and often contributes to the bionet.plants.education newsgroup. Hershey received his Ph.D. in plant physiology from University of California at Davis.
http://www.fortunecity.com/greenfield/clearstreets/84/bio.htm

Avoid Misconceptions When Teaching About Plants

Wisconsin Fast Plants

These small, fast-growing plants are excellent for classroom experiments and have been successfully used by thousands of teachers.
http://www.fastplants.org

Plant education resources

This goal of this website is to act as a repository for resources that can be used for plant science education or outreach.
http://knowplants.org/default.aspx

C-Fern

This small, easily grown fern is excellent for a wide variety of classroom experiments.
http://cfern.bio.utk.edu/

Science and Plants for Schools (SAPS)

This program promotes plant science teaching and is based in Great Britain. The web site contains much useful information, including practical investigations for students and a “Questions and Answers” section.
http://www-saps.plantsci.cam.ac.uk/

Essential Elements for Plant Growth

Phillip Barak of the University of Wisconsin provides an excellent discussion of a key topic often skipped over in many biology classes.
http://www.soils.wisc.edu/~barak/soilscience326/essentl.htm

Plants and Human Affairs

Dr. Stephen G. Saupe of the College of St. Benedict/St. John’s University site has many informative pages of course materials.
http://www.employees.csbsju.edu/SSAUPE/biol106/106_home.htm

For Educators and Students: textbooks

  • » Botany: An Introduction to Plant Biology, 3rd ed.
    This is a student web site for an introductory college botany textbook by Mauseth. It contains information on many plant topics.
    http://www.biology.jbpub.com/Botany/
  • » Biology of Plants, 5th ed.
    This is a student web site for the introductory college botany textbook by Raven, Evert, and Eichhorn. It contains information on many plant topics.
    http://bcs.whfreeman.com/raven7e/
  • » Principles of Botany
    This is a student web site for an introductory college botany textbook by Uno, Storey, and Moore. The site has a lot of valuable educational content.
    http://www.mhhe.com/biosci/pae/botany/uno/student/olc/chap01-summary.mhtml
  • » Plant Physiology, 4th ed.
    This is a web site for a leading college plant physiology textbook, by Taiz and Zeiger. The site contains much useful information on many plant topics.
    http://4e.plantphys.net/

Bionet.plants.education

This a listserve and newsgroup for plant science educators with a searchable archive. Teachers with questions on plants and teaching, including misconceptions, may submit them via email.
http://www.bio.net/hypermail/PLANT-EDUCATION/

Mad Scientist Network

A group of volunteer scientists answers science questions for students, teachers, and the general public. The site has well over one thousand answers to botany questions in the searchable archives.
http://www.madsci.org

Botanical Society of America

This site has a teaching section and often publishes teaching articles in its Plant Science Bulletin, which is available free online. There are many features useful to teachers, including a botany careers booklet, an image collection, and carnivorous plant information.
http://www.botany.org

  1. Carter, J. L. 2004. Developing a curriculum for the teaching of botany. _Plant Science Bulletin _50: 42-47. http://www.botany.org/bsa/psb/2004/psb50-2.pdf
  2. Amir, R., and P. Tamir. 1994. In-depth analysis of misconceptions as a basis for developing research-based remedial instruction: The case of photosynthesis. American Biology Teacher 56: 94-100.
  3. Canal, P. 1999. Photosynthesis and “inverse respiration” in plants: An inevitable misconception? International Journal of Science Education 21: 363-371.
  4. Ozay, E., and H. Oztas. 2003. Secondary students’ interpretations of photosynthesis and plant nutrition. Journal of Biological Education 37: 68-70.
  5. Wood-Robinson, C. 1991. Young people’s ideas about plants. _Studies in Science Education _19: 119-135.
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  8. Salisbury, F. B., and C. W. Ross. 1985. Plant Physiology. Belmont, CA: Wadsworth.
  9. Epstein, E. 1972. A blind spot in biology. Science 176: 235.
  10. Hershey, D. R. 1999. Myco-heterophytes and parasitic plants in food chains. American Biology Teacher 61: 575-578.
  11. Hershey, D. R. 2001. Knop’s solution is not what it seems. Science Activities 38(3): 17-20.
  12. McMenamin, J. P. 1948. Teaching the carrot root correctly. School Science and Mathematics 48: 47-48.
  13. Temple, S. A. 1977. Plant-animal mutualism: Coevolution with dodo leads to near extinction of plant. Science 197: 885-886.
  14. Hershey, D. R. 2000. The truth behind some great plant stories. _American Biology Teacher _62: 408-413.
  15. Witmer, M. C., and A. S. Cheke. 1991. The dodo and the tambalacoque tree: An obligate mutualism reconsidered. Oikos 61: 133-137.
  16. Muller, C. H. 1965. Inhibitory terpenes volatilized from Salvia shrubs. Bulletin of the Torrey Botanical Club 92: 38-45.
  17. Bartholomew, B. 1970. Bare zone between the California shrub and grassland community: The role of animals. Science 170: 1210-1212.
  18. Hershey, D. R. 1996. Allelopathy experiment pitfalls. Journal of Biological Education 30: 13-14.
  19. McGregor, S. E. 1976. Insect Pollination of Cultivated Crop Plants. USDA Agriculture Handbook No. 496. Washington (DC): GPO. http://gears.tucson.ars.ag.gov/book/index.html 8/24/10 Link no longer available.
  20. Cook, R. E. 1983. Clonal plant populations. American Scientist 71: 244-253
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  23. Lonergan, T. A. 2000. The photosynthetic dark reactions do not operate in the dark. American Biology Teacher 62: 166-170.
  24. Hershey, D. R. 1992. Is hydrotropism all wet? Science Activities 29(2): 20-24.
  25. Brown, P. H., and H. Hening. 1998. Boron mobility and consequent management in different crops. Better Crops with Plant Food 82: 28-31. http://www.back-to-basics.net/fertilityfacts/pdf_files/boron_mobility.pdf
  26. Hartmann, H. T., and D. E. Kester. 1983. Plant Propagation: Principles and Practices. 4th ed. Englewood Cliffs (NJ): Prentice-Hall.
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  28. Hershey, D. R. 2003. Misconceptions about Helmont’s willow experiment. Plant Science Bulletin 49: 78-84. http://www.botany.org/bsa/psb/2003/psb49-3.html
  29. Benzing, D. H. 1980. The Biology of the Bromeliads. Eureka, CA: Mad River Press.
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