Q. Can plants and trees sense when they're being cut or chopped down?A. It depends on how you define "sense, " said UW-Madison botany professor Edgar Spalding.
In the strictest terms, sensing is something that only sentient beings, such as people, can do. That is, we 're able to perceive a pin prick because the nervous system -- topped off by a brain -- creates an awareness of the prick from signals emanating from the injured cells.
By this definition, plants wouldn 't sense the same pin prick because they lack such higher-order processing, Spalding said. "But if we adopt a broader definition -- one that counts any reaction to a stimulus as sensation -- then the answer is definitely yes. Plants do sense wounding. "
Cutting or burning a leaf, for example, can trigger an electrical impulse that travels quickly to other parts of the plant. And merely touching a plant causes a temporary spike of calcium within cells.
What 's more, a caterpillar chewing a leaf can initiate the production of chemicals that help protect the plant, and may even signal to un-chewed plants that trouble is near.
The line between the ways in which animals and plants sense stimuli also seems to be blurring, Spalding added. Scientists have discovered that plant DNA encodes neurotransmitter receptors similar to those required for cognition in animal brains. "This question about what plants sense ' may get harder to answer before it gets easier, " he said.
-- Produced in cooperation with University Communications
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