Smarty Plants

      I am fascinated by the growing body of research on plant behavior.  That’s right–behavior.  While ‘behaving’ seems to be the province of animals and not of plants, scientists are learning about a variety of ways in which plants ‘behave’ in ways that are comparable to animal behavior.  Plants move, and they release chemicals that help them find food, improvethe soil where they are planted, and call for help.  Some researchers cite evidence that plants even ’learn’ from past experience.

     Plant growth is not just a matter of moving upward toward the sun.  Time-lapse photography shows that the leaves and stems of growing plants make eerie, circular, sweeping movements.  These movements, called nutation, occur because shoots grow unevenly, with the cells on one side elongating faster than the cells on the other.  “Over hours or days, the growing tip moves like a turning searchlight,” reports Susan Milius in Science News (6/20/09).   

     At the root end, plants ‘hunt for food’ by sending out roots.  Scientists have learned that root growth is directed toward areas of ground where nourishment is likely to be found, and away from ’dead zones that offer little nourishment. 

     Plants can even improve the nourishment available to them in the soil where they are planted, researchers say.  When scientists placed fava bean plants into a phosphorus-poor agar gel, the plants acidified the material around their roots.  This caused an increase of other substances in the gel that lowered the gel’s pH significantly within hours.  A lower soil pH increases plants’ uptake of phosphorus, a substances plants need.

     Not only do plants move more than we think they do, seek the most nourishing soil, and alter soil to meet their needs, but some even call for help when under attack!  For example, when mites or caterpillars bite into a plant’s leaves or stem, the plant releases volatile chemicals.  These chemicals often attract another insect species that typically preys on the first species.  The second group devours the first, thus protecting the plant.  Further, scientists have found that the predatory insects respond selectively.  While they will ‘protect’ plants being attacked by insects they like to eat, the insects do not protect plants being attacked by insects they do not typically eat.

     Plants ‘learn’ from the experience of other plants, and from their own as well.  For example, plants have been shown to heighten their own defenses when a neighboring plant releases the chemicals that indicate it is under attack. 

     A poplar leaf once scarred in an insect attack kicks its defense genes into high gear faster during a second attack than does a leaf during a first attack, reports Consuelo De Moraes, a researcher at Penn State University.  When De Moraes ‘attacked’ one poplar leaf, the released volatile chemicals wafted to neighboring leaves with ‘information’ about the nature of the attack.  When the scientist ’attacked’ these leaves later, they responded more quickly than did leaves that were prevented from receiving the informative volatile chemicals.  Getting the word out made a difference, it seems. 

     Plants are far more sophisticated actors, learners, and communicators than most of us ever imagined!–April Moore

4 Responses to “Smarty Plants”

  1. John Cochrane Says:

    Hi April,
    I am more and more impressed with Albert Schweitzer’s Reverence for Life – all life– Thank you for raising consciousness. Plants are like people, maybe not. But that plants adapt to environment and clearly chemically change , there is hope after all.

  2. Joan Brundage Says:

    How fascinating! Long ago, I did a science project growing bean plants. I noticed that the plants I hovered over and gave lots of attention to, got much bigger than the later bean plants outside in the garden. And the plants which partially broke their stems and were “bandaged back together” with just a human bandage, healed and grew larger stems around the break, much like a human’s broken finger joint often becomes larger when healed.

  3. Jessica Says:

    Neat article about plants’ consciousness. How precious our world is!

  4. Judy Says:

    April, I love the fascinating stories that you tell us. I have learned so much from you. Thank you.

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