But can they mope and write bad poetry? (Thinking plants)

I once put a passage from Aldous Huxley’s Jesting Pilate in front of an associate who suffers a bizarre malady afflicting his objectivity. Now, obectivity, while important, isn’t the biggest deal in the world; people are subject to all manner of quirks about their outlooks. But it’s a particular object of pride for him. To wit, he doesn’t like religion because faith isn’t objective.

But when it comes to vegetarianism, he is completely bent. People who eat meat are akin to those who rape and kill children, by his “objective” logic, and when one dangles the excerpt from Huxley, or a passage from Douglas Adams in front of him, he goes into this long explanation of how plants don’t have a central nervous system, don’t feel pain, and are thus exempt from the moral considerations of the torture involved in killing and eating an animal.

So, yes, I think of him every time I come across one of these stories in the news. The latest comes from the BBC, and is no surprise to me insofar as I expected something along these lines. Not being a botanist, however, I could only guess at what the data would look like:

Plants are able to “remember” and “react” to information contained in light, according to researchers.

Plants, scientists say, transmit information about light intensity and quality from leaf to leaf in a very similar way to our own nervous systems.

These “electro-chemical signals” are carried by cells that act as “nerves” of the plants.

In their experiment, the scientists showed that light shone on to one leaf caused the whole plant to respond.

And the response, which took the form of light-induced chemical reactions in the leaves, continued in the dark.

This showed, they said, that the plant “remembered” the information encoded in light.

“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.

He presented the findings at the Society for Experimental Biology’s annual meeting in Prague, Czech Republic.

“And the changes proceeded when the light was off… This was a complete surprise.”

In previous work, Professor Karpinski found that chemical signals could be passed throughout whole plants – allowing them to respond to and survive changes and stresses in their environment.

But in this new study, he and his colleagues discovered that when light stimulated a chemical reaction in one leaf cell, this caused a “cascade” of events and that this was immediately signalled to the rest of the plant by via specific type of cell called a “bundle sheath cell”.

The scientists measured the electrical signals from these cells, which are present in every leaf. They likened the discovery to finding the plants’ “nervous system”.

The ants go marching ….

Okay, so this is like really, really cool. Victoria Gill, writing for BBC, lets us in on the coolness:

In Africa and in the tropics, armies of tiny creatures make the twisting stems of acacia plants their homes.

Aggressive, stinging ants feed on the sugary nectar the plant provides and live in nests protected by its thick bark.

This is the world of “ant guards”.

The acacias might appear overrun by them, but the plants have the ants wrapped around their little stems.

These same plants that provide shelter and produce nourishing nectar to feed the insects also make chemicals that send them into a defensive frenzy, forcing them into retreat.

It is actually a fairly intricate relationship, with the ants territorially protecting a food source, including the swarming of larger herbivores, and the tree being able to chemically prevent the ants from causing too much havoc. Dr. Nigel Raine, at University of London, explained:

“The flowers seem to produce chemicals that are repellent to the ants,” said Dr Raine. “They release these particularly during the time when they’re producing lots of pollen, so the ants are kept off the flowers.”

In recent studies, described in the journal Functional Ecology, Dr Raine and his colleagues found that the plants with the closest relationships with ants – those that provided homes for their miniature guard army – produced the chemicals that were most effective at keeping the ants at bay.

“And that was associated with the flower being open,” he says. “So the chemicals are probably in the pollen” ….

…. The repellent chemicals are specific to the ants. In fact, they attract and repel different groups of insects.

“[The chemicals] don’t repel bees, even though they are quite closely related to ants. And in some cases, the chemicals actually seem to attract the bees,” says Dr Raine.

The researchers think that some of the repellents that acacias produce are chemical “mimics” of signalling pheromones that the ants use to communicate.

“We put flowers into syringes and puffed the scent over the ant to see how they would respond, and they became quite agitated and aggressive” he explained.

“The ants use a pheromone to signal danger; if they’re being attacked by a bird they will release that chemical that will quickly tell the other ants to retreat.”

Dr Raine says this clever evolutionary system shows how the ants and their plants have evolved to protect, control and manipulate each other.

Rediscovery: Plants are alive

I’m not going to complain about Natalie Angier‘s opinion piece in today’s New York Times:

In his new book, “Eating Animals,” the novelist Jonathan Safran Foer describes his gradual transformation from omnivorous, oblivious slacker who “waffled among any number of diets” to “committed vegetarian.” Last month, Gary Steiner, a philosopher at Bucknell University, argued on the Op-Ed page of The New York Times that people should strive to be “strict ethical vegans” like himself, avoiding all products derived from animals, including wool and silk. Killing animals for human food and finery is nothing less than “outright murder,” he said, Isaac Bashevis Singer’s “eternal Treblinka.”

But before we cede the entire moral penthouse to “committed vegetarians” and “strong ethical vegans,” we might consider that plants no more aspire to being stir-fried in a wok than a hog aspires to being peppercorn-studded in my Christmas clay pot. This is not meant as a trite argument or a chuckled aside. Plants are lively and seek to keep it that way. The more that scientists learn about the complexity of plants — their keen sensitivity to the environment, the speed with which they react to changes in the environment, and the extraordinary number of tricks that plants will rally to fight off attackers and solicit help from afar — the more impressed researchers become, and the less easily we can dismiss plants as so much fiberfill backdrop, passive sunlight collectors on which deer, antelope and vegans can conveniently graze. It’s time for a green revolution, a reseeding of our stubborn animal minds.

When plant biologists speak of their subjects, they use active verbs and vivid images. Plants “forage” for resources like light and soil nutrients and “anticipate” rough spots and opportunities. By analyzing the ratio of red light and far red light falling on their leaves, for example, they can sense the presence of other chlorophyllated competitors nearby and try to grow the other way. Their roots ride the underground “rhizosphere” and engage in cross-cultural and microbial trade.

“Plants are not static or silly,” said Monika Hilker of the Institute of Biology at the Free University of Berlin. “They respond to tactile cues, they recognize different wavelengths of light, they listen to chemical signals, they can even talk” through chemical signals. Touch, sight, hearing, speech. “These are sensory modalities and abilities we normally think of as only being in animals,” Dr. Hilker said.

Indeed, I’m glad to see it. But I wanted to point out that this isn’t exactly news.