This is a very interesting article that has the unfortunate title “Plants Can Think And Remember.” (Unfortunate because the many links to it that I have seen come with snarky comments like “Whatcha gonna do now vegetarians??”)
It reminds me of a great joke: Three scientists are on the committee to decide mankind’s greatest invention. The engineer is arguing for the internal combustion engine, the doctor is arguing for the X-ray machine and Martha Stewart is arguing for the Thermos. “The Thermos, you’ve got to be kidding?” Sez Martha “Well you see it keeps hot things hot and cold things cold.” They look perplexed. “Yeah, big deal.” Martha: “How does it know??”
The article is about some pretty sophisticated ways that plants respond to signals in their environment. That is very cool. Kudos to the Plant Kingdom. But while, there may be something in the underlying research that justifies saying that plants “think”, I rather doubt it, and it is definitely not to be found in this journalistic account. Look:
In their experiment, the scientists showed that light shone on to one leaf caused the whole plant to respond.
“We shone the light only on the bottom of the plant and we observed changes in the upper part,” explained Professor Stanislaw Karpinski from the Warsaw University of Life Sciences in Poland, who led this research.
When I light a match to the coals at the bottom of my charcoal chimney, eventually all of them ignite and turn red even the ones on the top. My charcoal can think.
Then there’s stuff about “memory.” But I already knew that plants had memory. When I give my grass water today, it is green next week. When I don’t give my grass water today, it is brown next week. The grass changes its color next week depending on whether I give it water today. It remembers.
Cheap Talk 
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July 27, 2010 at 11:11 pm
Bo
Your assertions, while understandable, are based on incorrect analogies. When you light a match to the coals at the bottom of your charcoal chimney, eventually all of them do ignite.. because heat rises and eventually the ambient temperature of the top charcoal reaches the point of ignition. What they are describing is the opposite. If you cast light on the top leaves, it is understandable that they might cause chemicals to be generated that gravity pulls down, and that those chemicals might cause a reaction lower. What they’ve described flies in the face of that. They induced a reaction at the base and the chemical response ran the wrong way — The top responded, suggesting that the plant itself intentionally expended some energy to send a message. That’s why it’s important.
Your description of memory is likewise flawed. What you’ve described isn’t a function of retained data, it’s dehydration in the leaves and a breakdown in the makeup of the leaf. Again, it’s a reaction completely in keeping with the biochemistry of the leaf as forces act upon it. When light is emitted onto a single leaf, leaves throughout the plant respond to the specific qualities of that light and begin producing chemicals that may be useful for surviving the environmental conditions that are usually associated with that light quality. This again is the opposite of a basic reaction. This suggests, preprogrammed or not, a reaction to stimulus beyond simple biochemical response. That’s a big deal too.
I can completely understand skepticism in the article and they haven’t really put forward a strong or verified argument for the theories… but they have suggested some very provocative things and, if their experiment stands validation… it may change considerably the way we approach botany and horticulture.