The National Science Education Standards (NSES) provide a framework for teaching precollege science.28 However, it does not stress the fundamental importance of plants in science teaching.
Common Frogbit (Hydrocharis morsus-ranae). Seagrasses are often an overlooked group of plants. Source: Dictionaire des plantes suisses, 1853.
- A 1992 National Research Council (NRC) report emphasized that “our knowledge about the world around us is incomplete if we do not include plants in our discoveries, and it is distorted if we do not place sufficient emphasis on plant life.”27
- A 1990 NRC report urged that, “because plants are especially easy to grow and care for, students at every grade level should be involved with gardening projects…. Both domesticated and native plants should be grown and observed. The ecological and agricultural importance of plants should be a major point of emphasis. The historical importance of agriculture in the development of the human race provides an ideal opportunity to integrate the social and natural sciences.”26
The NSES does not have such strong statements about the importance of plants in science teaching nor does it even contain the words agriculture and gardening. It also does not address challenges unique to plant teaching. If students are to become knowledgeable about plants, teachers need to be aware of the following five challenges.
Don’t neglect plants
There is “a recognized tendency, even for knowledgeable biologists, to overlook, underemphasize or neglect plants when teaching introductory biology courses.”35 Too often, biology is “botany taught by a zoologist,” leaving students with “the popular delusion that biology is the study of animals.”29 This results in widespread ignorance about and underappreciation of plants.3,4,10,14,33,36
This underappreciation of plants is apparent in the NSES. For example, they include the statement, “All animals depend on plants. Some animals eat plants for food.” (p. 129) That greatly understates the importance of plants to civilization.
- Plants also provide oxygen and shelter for animals, including humans.
People depend on plants for energy, medicines, rubber, cotton, wood, paper, cardboard, inks, oils, soaps, perfumes, gums, resins, turpentine, pesticides, poisons, dyes, toys, and thousands of other products.20 An amazing statistic of our dependence on plants is that each gallon of gasoline is derived from 198,000 pounds of ancient plant matter.8
Environmental benefits of landscape plants include shade, cooling, noise abatement, screening of unsightly views, erosion prevention, and windbreaks.30
Plants provide inspiration for art, architecture, humor, poetry, and literature, as well as beauty, holiday decorations, tourist attractions, jobs, and hobbies such as gardening. They are also important in religion, as state trees, as state flowers, and on stamps, currency, coins, and flags.
Ancient trees are revered for their longevity, size, and connections to famous people, places, and events.21,24
Given the widespread ignorance of plants and plant neglect in biology classes, teachers need to make a special effort to assure that both they and their students learn about plants.
Ask students the bumper sticker question “Have You Thanked a Green Plant Today?” Have interesting suggestions ready to add to student replies, such as a “Zillion Uses for Corn,” cocklebur inspiring the invention of Velcro, use of osage orange as living barbed wire, use of chia (of ChiaPet fame) by Aztecs, and plant medicines such as quinine, aspirin, taxol, morphine, reserpine, digitalis, and vincristine.20
Grow odd and fascinating plants in the classroom, such as carnivorous plants, sensitive plant, piggyback plant, resurrection plant, redwood burl, sea onion, prayer plant, and papyrus.
Use supermarket botany in one of the following ways:
- Assign each student a different aisle in the supermarket and see how many plant species they can find represented there.
- Have students identify what plant part—root, stem, leaf, flower, fruit or seed—they are eating for produce and processed foods.
- Grow plants from supermarket produce, such as ginger, carrot, potato, sweet potato and pineapple, date, star fruit, avocado, mango, pomegranate, papaya, citrus, peanut, and coffee.
- Include plants in other disciplines such as chemistry, history,11 and space science:
- Prepare hydroponic solutions to produce mineral nutrient-deficient plants and let students use semiquantitative chemical analysis to determine which mineral nutrient is missing.
- Study how plants cause pH shifts in hydroponic solutions.
- Study the chemistry of acid rain and its detrimental effects on plants.
- Examine the historical impact of crops such as potato, tea, cotton, corn, peanut, sugar cane, quinine, opium, tulip, and coca.
- Simulate plant growth in space or in a Mars colony.
Avoid animal chauvinism
Animal chauvinism, or zoochauvinism, is a bias against plants in favor of animals.6,17 It seems to afflict many biology teachers. A columnist for the American Biology Teacher, the leading journal for biology teachers, stated the bias this way: “We are all more interested in animals.”9 Of course that is not true. It is ironic that the two most prominent biologists in most biology texts were strongly interested in plants. Gregor Mendel studied inheritance in pea plants, and Charles Darwin wrote several books on plants. Prejudices against plants are illogical because if all plants became extinct, most of the human population would starve. We would survive quite nicely if all other animal species became extinct.
Leading high school textbooks devote just 14% of their chapters to plants, compared with 42% to animals and humans.34 Surveys indicate students prefer to study animals rather than plants.35,36 However, some of that may reflect the animal chauvinism of their teachers or society, or that many teachers don’t know enough about plants to teach botany well. As a teacher, be sure you are not biased against plants and devote sufficient time to plants. Teach students that plants are not only vital to human survival but are also fascinating organisms. Here are some suggestions:
Enhance the plant in a jar exercise (NSES pp. 92-97) with the intriguing stories of the accidental invention of the terrarium and of humans sealed inside Biosphere II, a giant terrarium in the Arizona desert.
Enrich the history of photosynthesis lecture (NSES pp. 194-196) by having students use the simple techniques of photosynthesis researchers in the 1600s and 1700s. For example, in 1699, John Woodward compared growth and water use of mint plants grown in glasses of water with various amounts of dissolved or suspended solids.18 Also use simple techniques that help students visualize photosynthesis.
The Science and Technology project for grades 5-8 (NSES pp. 161-164) could easily involve plants rather than an egg drop. Students could construct a hydroponic system from recycled and readily available materials and use it for plant experiments. Hydroponics experimentation should be an essential part of science teaching because it clearly disproves the widespread misconception that plants “eat” soil. The hydroponics display at Walt Disney World’s Epcot Center is its most popular exhibit, and students are usually fascinated by hydroponics.25
Emphasize dramatic plant concepts; for example, plants are the dominant organisms on land on a mass basis, and photosynthetic plants get most of their dry mass from a trace gas in the atmosphere. Plant dry matter is literally constructed out of thin air!
Have students compare and contrast animals and plants. In particular, compare human systems for mechanical support, “digestion, respiration, reproduction, circulation, excretion, movement, control, and coordination, and for protection” (NSES p. 156) with analogous plant systems. Most biology texts have chapters devoted to each human system but exclude plants from those chapters. Teachers should pick textbooks that discuss these basic biological functions, such as gas exchange, for all organisms together—animals, plants, fungi, and so on—rather than in taxonomically oriented chapters (i.e., chapters on gas exchange in animals, gas exchange in plants, etc.).
Connect human nutrition to plant function by asking students why plants are rich sources of fiber, vitamin A, and vitamin C.
Make plant teaching relevant to increase student interest.13 Traditionally, plant content in biology texts is basic, rather than applied yet science “Content is fundamental if it applies to situations and contexts common to everyday experiences.” (NSES p. 109). Here are examples: 15
- Application of apical dominance in pruning trees and shrubs.
- Use of plant hormones in agriculture, such as gibberellins to increase size of seedless grapes and ethylene to induce flowering in pineapple and ripen tomatoes.
- Application of differences in stem anatomy between monocots and dicots in grafting.
Don’t let science standards discourage plant use
State science standards often do not use plants as examples of basic biological concepts and sometimes exclude using plants in some situations.34 Plants provide excellent examples and experimental subjects for all the life science standards (NSES p. 106), yet the NSES sometimes excludes them:
- Pages 124-125 describe keeping a pet hamster in the classroom and using it in a study on evaporation from a watering can. However, a plant would make an excellent “pet” as well and would work better in an evaporation study given that plants evaporate large amounts of water.2 Measuring transpiration also was important in the history of photosynthesis research, unlike the contrived NSES scenario that the hamster escapes from its cage at night to drink water from the watering can. The more fundamental question is why plants have to be watered so frequently with the watering can.
Pages 128-129 talks about “behaviors that help various animals survive.” There was no logical reason to limit the concept to animals when it also applies to plants. The six-part BBC television series, “The Private Life of Plants,” is an excellent source for behaviors that help plants survive.1
Page 187 states, “The broad patterns of behavior exhibited by animals have evolved to ensure reproductive success. Animals often live in unpredictable environments, and so their behavior must be flexible enough to deal with uncertainty and change. Plants also respond to stimuli.” Plants should not just be mentioned as an afterthought. Plants also have “broad patterns of behavior…[that] have evolved to ensure reproductive success,” especially coevolution with animals that distribute a plant’s pollen and seeds.23 Plants have a greater problem with “unpredictable environments” because they cannot seek shelter as many animals can.
Teachers should not let science education standards prevent use of plants in the classroom. Plants offer many advantages for class experiments and demonstrations. They are inexpensive, readily available, easy to work with, and avoid ethical problems that may arise with animal experiments and dissections. The potential dangers and disposal problems of microbe cultures are also avoided. There are many inexpensive plants that do well under classroom conditions. Common houseplants, especially devil’s backbone and amaryllis, are excellent. There are two marvelous model plants for teaching, Fast Plants and C-Fern. Plant growth experiments also satisfy the recommendation (NSES p. 113) for more emphasis on “investigations over extended periods of time.”
Don’t be fooled by authors “practicing botany without a license”
Many science teaching materials contain misconceptions about plants because the authors have insufficient plant training. For example, a Smithsonian Institution website states that “hardworking bees pollinated the potato plant that eventually became potato chips and French fries.”31 That is misleading because no pollination is required given that the edible potato tuber, an underground stem, is not a flower, fruit, or seed. Most cultivated potatoes are asexually propagated.
There are hundreds of errors or misconceptions about plants in the teaching literature, so teachers need to be on guard for them.19 Even refereed biology teaching journals occasionally publish very inaccurate plant articles. Four letters to the editor of American Biology Teacher pointed out numerous errors in one botany teaching article penned by zoologists.7
Plant misconceptions in the NSES include these:
- “Plants and some microorganisms are producers.” (p. 157) That is misleading because over 300 parasitic plant species are consumers and lack chlorophyll, among them the fabulous Rafflesia arnoldii with the world’s largest flower.1,16
“Plants also reproduce sexually—the egg and sperm are produced in the flowers of flowering plants…. That new individual receives genetic information from its mother (via the egg) and its father (via the sperm).” (p. 157) That is misleading because a self-pollinating plant acts as both parents, contributing both egg and sperm.
“Sexually produced offspring never are identical to either of their parents.” (p. 157). Although uncommon, a single homozygous parent can produce sexual offspring that are genetically identical to it. That is the basis of self-pollinated crops that come true from seed, such as the pea cultivars Mendel started with in his experiments, plus crops such as tomato, soybean, rice, and wheat. Such crops produce offspring that are very nearly identical to their self-pollinated parents.
“Only mutations in germ cells can create the variation that changes an organism’s offspring.” (p. 185) That is not exactly true in plants that reproduce asexually or are asexually propagated. Plant cloning is very important in many wild species and especially in agriculture.5 Mutations in vegetative cells have been responsible for thousands of new cultivars. Examples include many plants with variegated leaves due to chimeras and hundreds of apple cultivars that arose from bud sports such as Red Fuji, a sport of Fuji, and Royal Gala, a sport of Gala.22
Science teachers should be wary of plant teaching materials written by nonbotanists. Plant project books written by nonbotanists often contain numerous misconceptions, so teachers may wish to screen them before recommending them to students. Teachers with questions about potential plant misconceptions should query madsci.org or the bionet.plants.education newsgroup.
Deal with plant pseudoscience and anthropomorphisms
Plant pseudoscience includes widespread beliefs that plants grow better when sown during certain phases of the moon, that plants have ESP, and that plants grow better when people talk to them, say prayers for them, or play certain types of music. Certain products for plant growth are also pseudoscientific, such as many exotic plant fertilizers and biostimulants. Metal probe meters to measure soil pH, fertility, and water content are ineffective yet are sold by science education suppliers.12 Whether music affects plant growth is a very popular student science project, but precollege students lack the equipment and facilities to properly perform such experiments. Teachers should guide students to avoid pseudoscience projects. There are plenty of valid student projects with plants.
Several types of plant pseudoscience are anthropomorphic, such as supposed beneficial effects of music, talking, and human medicines on plant growth. The NSES notes that anthropomorphism is common in young students, but they outgrow it as they gain knowledge. With widespread plant neglect, anthropomorphism with plants seems to persist longer. One of the most common questions at madsci.org comes from middle or high school students who irrigate plants with human beverages, such as coffee, tea, milk, and soda. Students are at a loss to explain their results because biology textbooks and the botany literature don’t discuss the topic. Teachers should guide students away from anthropomorphic plant projects by reminding them of the requirements for photosynthesis. Rather than irrigating plants with human beverages, students could irrigate plants with different types or concentrations of fertilizer solution.
“Plants are the most important, least understood, and most taken for granted of all living things.”36 To ensure that students understand and appreciate plants, don’t neglect plants in teaching. Avoid animal chauvinism by making plant studies fascinating and relevant. Don’t let science standards discourage plant use in the classroom. Don’t be fooled by authors practicing botany without a license. Effectively deal with student beliefs in plant pseudoscience and anthropomorphisms. Classroom ideas for teaching about plants are provided in the Get Involved Links below in the section “classroom reading, activities, and other resources.”
© 2005, American Institute of Biological Sciences. Educators have permission to reprint articles for classroom use; other users, please contact firstname.lastname@example.org for reprint permission. See reprint policy.