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The Intelligent Plant

On the Farm . . . what's happening this week

The farm has received 1 1/2 inches of much needed rain in the last two days. Before that our pump was running almost around the clock to water all the produce. While the cold weather yesterday felt weird, we are very thankful for the front that gave us rain. I wonder if the plants are thankful. Probably not, but new research is questioning whether or not plants have memory, sensory abilities and even to some degree - intelligence.

Michael Pollan, author of The Omnivore's Dilemma and In Defense of Food among others, wrote a interesting piece for the New Yorker in the December 23, 2013 issue called The Intelligent Plant. and was interviewed for Public Radio .

In it he says a controversial 2006 article in Trends in Plant Science proposed "a new field of inquiry that the authors, perhaps somewhat recklessly, elected to call “plant neurobiology.” The six authors—among them Eric D. Brenner, an American plant molecular biologist; Stefano Mancuso, an Italian plant physiologist; František Baluška, a Slovak cell biologist; and Elizabeth Van Volkenburgh, an American plant biologist—argued that the sophisticated behaviors observed in plants cannot at present be completely explained by familiar genetic and biochemical mechanisms. Plants are able to sense and optimally respond to so many environmental variables—light, water, gravity, temperature, soil structure, nutrients, toxins, microbes, herbivores, chemical signals from other plants—that there may exist some brainlike information-processing system to integrate the data and coördinate a plant’s behavioral response. The authors pointed out that electrical and chemical signalling systems have been identified in plants which are homologous to those found in the nervous systems of animals. They also noted that neurotransmitters such as serotonin, dopamine, and glutamate have been found in plants, though their role remains unclear."

The article is too long to share everything but some of the interesting points follow:

•Pollan says "Plants can do incredible things. They do seem to remember stresses and events . . . They do have the ability to respond to 15 to 20 environmental variables," Pollan says. "The issue is, is it right to call it learning? Is that the right word? Is it right to call it intelligence? Is it right, even, to call what they are conscious. Some of these plant neurobiologists believe that plants are conscious — not self-conscious, but conscious in the sense they know where they are in space ... and react appropriately to their position in space." He also says that really freaks people out — "that the line between plants and animals might be a little softer than we traditionally think of it as." He suggests that plants may be able to teach humans a thing or two, such as how to process information without a central command post like a brain.

•Several species, including corn and lima beans, emit a chemical distress call when attacked by caterpillars. Parasitic wasps some distance away lock in on that scent, follow it to the afflicted plant, and proceed to slowly destroy the caterpillars. Some are hopeful studying plant distress signals could help prime plant defenses reducing dependence on pesticides.

•Stefano Mancuso, one of the aforementioned authors, is working on a dictionary of each plant species’ entire chemical vocabulary. He estimates that a plant has three thousand chemicals in its vocabulary compared with an average student’s seven hundred words.

•“I agree that humans are special,” Mancuso says. “We are the first species able to argue about what intelligence is. But it’s the quantity, not the quality” of intelligence that sets us apart. We exist on a continuum with the acacia, the radish, and the bacterium. “Intelligence is a property of life,” he says. I asked him why he thinks people have an easier time granting intelligence to computers than to plants. (Fred Sack told me that he can abide the term “artificial intelligence,” because the intelligence in this case is modified by the word “artificial,” but not “plant intelligence.” He offered no argument, except to say, “I’m in the majority in saying it’s a little weird.” Mancuso thinks we’re willing to accept artificial intelligence because computers are our creations, and so reflect our own intelligence back at us. They are also our dependents, unlike plants: “If we were to vanish tomorrow, the plants would be fine, but if the plants vanished . . .” Our dependence on plants breeds a contempt for them, Mancuso believes. In his somewhat topsy-turvy view, plants “remind us of our weakness.”

•There is also a video of a bean plant using time-lapse photography that shows a bean plant reaching for a metal pole is seems to be focused on climbing without wasting any time “looking” for anything else to climb, maybe utilizing echolocation. It seems to be exhibiting intention.

This is fascinating to me, and given all that I learned reading these articles, I’m sure our eggplants have been screaming - ok, emitting volatile chemicals, signals to other leaves as well as nearby eavesdropping plants to mount a defense. They may have even been sharing information obtained from the taste of the flea beetles that are chewing up their leaves hindering their ability to photosynthesize.

A few days ago we had noticed a couple of the plants on the end of the row didn't look quite as robust as the others. They had some flea beetle holes in their leaves as all the eggplants typically do being favorites of flea beetles. We always have some flea beetle damage but at low levels that don't affect the plant's health. The beneficial microbes we've applied to the soil kept them in check past seasons. Bill thought the plants hadn't received enough water due to their location, and because it was windy the day he had the sprinklers on them so he watered them again. But the problem got worse, and we now know the culprit is indeed flea beetles.

A new batch must have hatched and for whatever reason our beneficial microbes didn’t mount a satisfactory defense (next year we plan to apply more often and utilize row cover). After harvesting the fruits yesterday, we squished millions of normally very nimble but now cold and lethargic flea beetles on the leaves while reassuring the plants (yes, we are a little kooky) and feeling no sympathy for the marauding insects. We are hopeful we eliminated enough to not only save the plants but also in a timely fashion so they can produce more of the beautiful, dark purple globes.

And while I can’t actually hear our plants out in the field, I’m imagining they are very quiet and happily quenched of their thirst for now.

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