American Biology Teacher Guest Editorial


Mon Dec 6 09:15:20 EST 2004


dh321 at excite.com

Organization: 	BIOSCI/MRC Rosalind Franklin Centre for Genomics Research
To: 	bionet-plants-education at net.bio.net
Newsgroups: 	bionet.plants.education



[I guess that didn't work!  If this doesn't look better I'm giving up.  
- moderator]

The following manuscript was accepted as a guest editorial by American 
Biology Teacher editor Randy Moore in November 2002. However, the 
Managing Editor much later informed me that the manuscript had been 
misplaced and would not be published because she felt it was no longer 
timely. Appeals to the new Editor, Publisher, NABT President and ABT 
Journal Advisory Committee were acarpous so I thought I would make it 
available here.

David R. Hershey
dh321 at excite.com

Plants Are Indeed Intelligent

Biology Today columnist Maura Flannery (2002) rejected Anthony Trewavas 
(2002) thesis that plants have intelligence mainly by assuming it was 
merely an "animal metaphor". However, Trewavas (2002) was not being 
metaphorical, he was being literal. Flannery (2002) arbitrarily 
restricted the term intelligence to "an animal way of doing things." 
However, Webster's dictionaries don't restrict intelligence to animals.

Webster's dictionaries define intelligence as "the ability to cope with 
a new situation" (Agnes 2002) or "the ability to learn or understand or 
to deal with new or trying situations" (Woolf 1973). Flannery (2002) 
described how plants cope with new or trying situations such as high 
temperatures, water deprivation, and attacks by herbivores and 
pathogens. Therefore, no "animal metaphor" is required. Plants literally 
fit a dictionary definition of intelligence. Trewavas (2002) said 
effectively the same thing as Webster; plants are intelligent because 
they have "adaptively variable behavior." Trewavas (1999) has evidence 
that plants learn, which also qualifies as intelligence according to the 
dictionary definition.

Flannery (2002) stated that all animals, "even a slug", have higher IQs 
than any plant. However, several plant species are intelligent enough to 
produce caffeine, which Flannery (2002) noted is a highly effective 
pesticide against slugs. Was the inventor of Velcro, George de Mestral, 
more intelligent than the cocklebur (Xanthium stumarium) which gave him 
the idea (Jacobs 1996)? Was Joseph Paxton, the designer of London's 
famous Crystal Palace of 1851, more intelligent than the giant waterlily 
(Victoria amazonica) whose leaf venation inspired his design (Carter 
1985)? Are the chemists who first synthesized taxol in the laboratory 
more intelligent than the Pacific yew (Taxus brevifolia) which 
synthesized it first and provided them with the structure of taxol? Are 
the thousands of plant products in a supermarket just an indication of 
human accomplishment or do plants deserve some credit? Humans often take 
sole credit for accomplishments that were really made by plants. Many 
people do not seem to realize that "Man and all other animals are in 
reality guests of plants on this earth" (Karling 1956).

If the modern Plant Kingdom, consisting of bryophytes and vascular 
plants, was suddenly wiped out, humans would not be able to respond to 
the "trying situation" without mass starvation. Humans might even go 
extinct due to wars over, or overexploitation of, the remaining food 
chains anchored by algae and photosynthetic bacteria. However, if humans 
were suddenly wiped out, plants would actually benefit in several ways 
because they could recolonize all the areas occupied by buildings and 
paving and would no longer have the destructive effects of humans 
destroying their habitats, overcollecting wild plant species into 
extinction, introducing nonnative invasive plants, and polluting the 
air, water and soil. Even if all animals were wiped out, the many plant 
species that do not depend on animals for pollination and seed dispersal 
would not be negatively impacted. Even many of the plants that coevolved 
with animals might be able to survive without them.

Common themes in science fiction, and goals of real science, are human 
cloning and suspended animation for long space voyages. However, plants 
have used cloning and suspended animation for over 100 million years. 
Seeds can survive in suspended animation for decades or centuries 
(Shen-Miller et al. 1995). Plants have numerous cloning methods such as 
adventitious plantlets, apomictic seeds, bulbs, corms, fragmentation, 
layering, rhizomes, runners, suckers, and tubers.

Flannery (2002) noted the "problem" Trewavas (2002) was addressing as 
"the view of plants as passive and therefore not very interesting 
organisms". However, Trewavas (2002) was only dealing with the view of 
plants as passive. He never stated or implied that plants were "not very 
interesting." Given that Flannery (1999) wrote a column on plant 
blindness, it would have been much more desirable to have stated the 
problem more accurately, i.e. "Although a common misconception, it is a 
huge mistake to view plants as passive or uninteresting." Flannery 
(1999) actually dismissed the misconception of plants as uninteresting 
rather well when she asked "Why deprive ourselves of the joy of learning 
about organisms that have come up with so many fascinating strategies to 
deal with the challenge of life on Earth."

How can parasitic and carnivorous plants be considered passive when they 
are stealing energy and nutrients from other plants or murdering 
animals, respectively? The strangler figs (Ficus aurea and other Ficus 
spp.) are notorious for murdering their host trees. Plants are 
constantly battling each other to the death. Even seemingly harmless 
epiphytes are considered "nutritional pirates" who intercept mineral 
nutrients and effectively steal from their host trees (Benzing 1980). 
Plants may be stationary but their seeds or fruits may fly, float, be 
forcibly discharged or carried by animals to other locations. Fruits of 
coconut (Cocos nucifera) may float for hundreds of km in the ocean, and 
the fruit of the sandbox tree (Hura crepitans) explodes like a hand 
grenade when it dries and can forcibly discharge its seeds up to 100 m 
(Ray et al. 1983).

Plants also face hordes of herbivores and pathogens, resource shortages 
and harsh environments. It is hardly passive that plants use a multitude 
of mechanical and chemical weapons and ally themselves with a variety of 
bacteria, fungi and animals in their battle for survival. Their allies 
include nitrogen-fixing bacteria, mycorrhizal fungi, animal pollinators, 
animal seed dispersers, fungal and bacterial endophytes and even ants 
that serve as live-in bodyguards. Plants not only communicate with other 
plants, they communicate with their allies. For example, an Acacia tree 
produces a chemical in its flowers that tells its ant bodyguards not to 
attack the insect pollinators that visit the flowers (Ghazoul 2001).

The sizzling sex life of plants is hardly passive either. Plants flaunt 
their sex organs and often advertise them with flashy petals or bracts, 
delicious fragrances or a horrible stench. Some flowers even generate 
heat to attract pollinators or better disperse floral scents (Seymour 
1997). Jack-in-the-pulpit (Arisaema triphyllum) changes its sex 
depending on the resources available (Policansky 1987). Plants fill the 
air with untold trillions of pollen grains. Plants sometimes even trick 
animals into pollinating their flowers or dispersing their seeds without 
giving them the expected rewards.

Contrary to Flannery (2002), I think it is a fundamental requirement 
that students be able to contrast animal and plant strategies to deal 
with basic challenges, such as energy accumulation, environmental 
sensing, solid and liquid intake, gas exchange, waste disposal, internal 
transport, mechanical support, temperature control, defense, growth and 
reproduction. If students are not able to describe how plants meet these 
basic biological challenges, then they are suffering from plant 
blindness. Darley (1990) noted that plants' nutritional mode requires 
them to be stationary because they are "collectors and concentrators" 
and concluded that "If we feel animals are superior, it is only because 
we are animal chauvinists". Whether called animal chauvinism, plant 
blindness or plant neglect (Hershey 1993, 2002, Hoekstra 2000, Wandersee 
and Schussler 1999), the problem remains that there are many biology 
teachers, and thus their students, "whose familiarity with plants is 
little more than skin-deep" (Nichols 1919). Perhaps Trewavas (2002) 
discovery that plants are intelligent will make biology teachers take 
plants a bit more seriously.

David R. Hershey
dh321 at excite.com

Literature Cited

Agnes, M. E. (2002). Webster's New World Compact Desk Dictionary and 
Style Guide. New York: Hungry Minds.

Benzing, D.H. (1980). Biology of the Bromeliads. Eureka, California: Mad 
River Press.

Carter, T. (1985). The Victorian Garden. New York: Salem House.

Darley, W.M. (1990). The essence of "plantness." American Biology 
Teacher, 52, 354-357.

Flannery, M.C. (1999). Seeing plants a little more clearly. American 
Biology Teacher, 61, 303-307.

Flannery, M.C. (2002). Do plants have to be intelligent? American 
Biology Teacher, 64, 628-633.

Ghazoul, J. (2001). Can floral repellents pre-empt potential ant-plant 
conflicts. Ecology Letters, 4, 295-299.

Hershey, D.R. (1993). Prejudices against plant biology. American Biology 
Teacher, 55, 5-6.

Hershey, D.R. (2002). Plant blindness: "We have met the enemy and he is 
us." Plant Science Bulletin, 48, 78-85.

Hoekstra, B. (2000). Plant blindness: The ultimate challenge to 
botanists. American Biology Teacher, 62, 82-83.

Jacobs, M.I. (1996). Unzipping Velcro. Scientific American, 274(4), 116.

Karling, J.S. (1956). Plants and man. American Biology Teacher, 18, 9-13.

Nichols, G.E. (1919). The general biology course and the teaching of 
elementary botany and zoology in American colleges and universities. 
Science, 50, 509-517.

Policansky, D. (1987). Sex choice and reproductive costs in 
jack-in-the-pulpit, BioScience, 37, 476-481.

Ray, P.M., Steeves, T.A. and Fultz, S.A. (1983). Botany. Philadelphia: 
Saunders.

Seymour, R.S. (1997). Plants that warm themselves. Scientific American, 
276(3), 104-109.

Shen-Miller, J., Mudgett, M.B., Schopf, J.W., Clarke, S. and Berger, R. 
(1995). Exceptional seed longevity and robust growth: Ancient sacred 
lotus from China. American Journal of Botany, 82, 1367-1380.

Trewavas, A, (1999). How plants learn. Proceedings of the National 
Academy of Sciences, 96, 4216-4218.

Trewavas, A. (2002). Mindless mastery, Nature, 415, 841.

Wandersee, J.H. and Schussler, E.E. (1999). Preventing plant blindness. 
American Biology Teacher, 61, 82, 84, 86.

Woolfe, H.B. (1973). Webster's New Collegiate Dictionary. Springfield, 
Massachusetts: G. and C. Merriam Company.

-----------------------------

Addendum: After the above Guest Editorial was written, Dr. Trewavas 
published a detailed invited review on plant intelligence which is 
available online:

Trewavas, A. 2003. Aspects of plant intelligence. Annals of Botany 92: 1-20
http://aob.oupjournals.org/cgi/content/full/92/1/1



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 Jonathan D. Monroe, Associate Professor
 Department of Biology, MSC 7801
 James Madison University, Harrisonburg, VA 22807
 office: 540-568-6649, fax: 540-568-3333
 email: monroejd at jmu.edu
 http://csm.jmu.edu/biology/monroejd/jmonroe.html
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