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Plants Can Recognize Kin July 5, 2009

Posted by Dwight Furrow in Dwight Furrow's Posts, Science.
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It is well known that animals act preferentially toward members of their own family or group. Now there is evidence that plants do as well.

Experiments show that a sagebrush plant can recognise a genetically identical cutting growing nearby.

What’s more, the two clones communicate and cooperate with one another, to avoid being eaten by herbivores.

The findings, published in Ecology Letters, raise the tantalising possibility that plants, just like animals, often prefer to help their relatives over unrelated individuals.

Here is a brief account of the experiment:

They took cuttings of Artemisia tridentata, a species of sagebrush that does not normally reproduce by cloning itself.

They placed each cutting either near its genetic parent, essentially its clone, or near an unrelated sagebrush, and let the plants grow in the wild in the University of California Sagehen Creek Natural Reserve. The researchers clipped each clone they planted, feigning damage that might be caused by natural herbivores such as grasshoppers.

After one year, they found that plants growing alongside their damaged clones suffered 42% less herbivore damage than those growing alongside damaged plants that were unrelated.

Somehow, the clipped plants appeared to be warning their genetically identical neighbours that an attack was imminent, and the neighbour should somehow try to protect itself. But clipped plants didn’t warn unrelated neighbours.

Of course, this does not mean that plants are conscious, aware, or feel empathy:

Karban suspects the plants are communicating using volatile chemicals. When one plant is clipped, or comes under attack from herbivores, it emits these chemicals into the air, warning those around it to put up a defence, either by filling their leaves with noxious chemicals, or by physically moving their stems or leaves in some way to make themselves less palatable.

The use of the words “recognize” “preferences” and “warning” are a bit misleading. Apparently some plants have evolved in such a way that they are sensitive to particular chemical changes in their environment that cause them to react with their own chemical changes, which confer protection.

Plants don’t “know” their kin or “know” they are being warned just as a thermometer doesn’t “know” it is 70 degrees outside.

book-section-book-cover2 Dwight Furrow is author of

Reviving the Left: The Need to Restore Liberal Values in America

or Visit the Website: www.revivingliberalism.com