The Trees Are Talking

Candice Gaukel Andrews September 20, 2011 9

The trees are most likely talking over your head. ©Henry H. Holdsworth

If you’ve ever walked in a forest or a grove on a breezy or windy day, you’ve probably experienced that bit of an unsettling feeling that says to you that the trees are “talking” above your head. With every moan and retort of the wood, you’d almost swear that you could hear rumblings. Much like the trees in the film the Wizard of Oz that get annoyed with Dorothy after she picks an apple from one of them and then they begin to throw apples back at her, the trees surrounding you on your walk seem to be whispering to each other about the propriety of your presence.

Turns out that your intuition may not be so far from the truth. Scientists are now discovering that plants have similar senses to ours and that they “talk” to each other—not through their roots, but as we do: through the air.

Defense talks

These aspens are probably discussing the moose in their midst. ©Henry H. Holdsworth

We’ve known for a long time that plants are sensitive to their environments, reacting to changes in temperature, soil conditions and light. Their senses, like ours, are quite developed: the Venus flytrap catches its dinner by snapping shut when an insect touches the tiny hairs on its leaves, and some farmers believe that sounds louder than the human voice stimulate the germination and rapid growth of some vegetables. But the confirmation that plants of the same species are able to talk with each other through the air is a new development.

In one recent research project, scientists took note of when the first gypsy moth larvae landed on a mature oak tree that resided in a grove with other oaks. By analyzing the chemistry of the mature oak tree’s leaves, they were able to determine that within a very short period of time, the tree had added a bitter tannin to all of its leaves. The tannin made the tree an unattractive lunch option for the gypsy moth larvae. But what was more astounding was that all the other oak trees in the grove changed the chemistry of their leaves, too, making them unappetizing as well.

It took a few years for the scientists to understand just how the trees in the rest of grove had gotten word that the gypsy moths were in town. It was found that the trees did not communicate through their roots—instead, they released a special gas (or pheromone) to warn their neighbors of the danger.

Willow witnesses

It’s not only the oak trees that are chatting. We now have proof that willows, too, are talking with each other through the air. A chemist investigating how willows react when attacked by tent caterpillars provides verification.

The Great Bear Rainforest is the largest remaining intact coastal temperate rainforest in the world. ©Candice Gaukel Andrews

The chemist subjected two groups of willows to different conditions: one group was allowed to be invaded with tent caterpillars, while the second group was left to act as “witnesses”; in other words, left untouched. After 14 days, he picked up leaves from willows in both groups to feed to tent caterpillars, which this time were in the lab. He found that the lab caterpillars that ate small amounts of leaves from the willows that had had caterpillars were growing very slowly. But what was puzzling was that leaves from the untouched or “witness” group of willows were equally unpleasant for and caused the same result in the lab caterpillars.

Further analysis showed that both willow groups had filled their leaves with a chemical that proved to be repulsive for the insects. The message about the influx of tent caterpillars had been transported from willow group to willow group by ethylene, a gas normally produced during the reaping of fruits but also released by a willow’s harmed or irritated tissues.

These new reports are especially appropriate for this International Year of Forests. Now that we know for sure that trees talk through the air like we do, we have to wonder what they say about us as we press into their territories and begin to deforest the land, starting at one edge of the woods and working our way through to the other. Do the trees cut first shout to the others on the opposite end to run? Or are they whispering to us, asking that we be more mindful of the consequences?

Here’s to finding your true places and natural habitats,

Candy

9 Comments »

  1. Candice Gaukel Andrews March 11, 2015 at 6:29 am - Reply

    Shulamis,

    This article was written in 2011 (four years ago), so my original notes on this no longer exist. However, if you do a Google search, you’ll find many papers on this topic. As a start, these might be of help:

    http://www.wired.com/2013/12/secret-language-of-plants/

    http://onlinelibrary.wiley.com/doi/10.1111/ele.12205/full

    http://pubs.acs.org/doi/abs/10.1021/bk-1983-0208.ch004

    http://www.pnas.org/content/87/19/7713.long

    Thanks for your comment. —C.G.A.

  2. Shulamis March 10, 2015 at 1:14 pm - Reply

    Inspiring! but disappointing that no sources for any of those scientific studies were listed. Can they be provided?

  3. Sonja December 9, 2014 at 4:09 pm - Reply

    Pine trees actually make very loud audible conversation with each other, like a song. I’ve been to a number of locations and heard a very distinct hum coming from within individual trees. Interestingly they will each pass sounds back and forth to each other and sometimes they will chime together. I’ve taken a number of people to listen as most people think I’m imagining it until they hear it for themselves. It’s an amazing thing to hear.

  4. josh johnson September 8, 2013 at 12:32 pm - Reply

    My family does excavating and land clearing but i still love trees.it breaks my heart when we have to cut down trees but thats progress in the eyes of humanity right 🙁

  5. Manjoo Natah March 2, 2013 at 12:20 am - Reply

    hi,

    THe article is very tree friendly. Ijust have a feeling that the trees respond to human feeling……….Its just a feeling………nothing practical about it………

    Thanx.

  6. lenny lyons September 22, 2011 at 1:20 am - Reply

    This article reminds me of a short conversation I had with my son when he was about 6 years old, perhaps younger, I was “teaching” him about how the Giant Sequoia was the largest living thing on Earth. He looked at me with what I took to be innocent pity at how stupid his old man was and said, “No, duh.” When I asked him what was larger, he said…”a mountain.” I cherish that consciousness and I hope he got some of it from me.

  7. John Howard Gaukel September 21, 2011 at 12:34 pm - Reply

    This example of the trees “talking” to each other gives us more proof that we shouldn’t be so eager to destory what Mother Earth has given us. She has a lot to teach us about the flora and fauna that she has provided, if only we would take the time to look and understand. We should not be so eager to cut down a forest or fill in a marsh to build a super mall. How many drugs currently in use come from plants? Doesn’t the drug Taxol, which is commonly prescribed for women who are diagnosed with advanced ovarian and breast cancer, derived from the Pacific yew, once considered a worthless weed tree?

  8. Travis September 20, 2011 at 12:19 pm - Reply

    Sounds like a laissez faire argument as far as insect treatment goes?

  9. Kate Robson September 20, 2011 at 8:45 am - Reply

    Great article. Some Native Americans call trees with ‘crossed branches’ that rub against each other talking trees. Please forgive my poor attempt at poetry, but I wrote this many years ago: The Forest
    Mighty oaks stand proud and tall in their slumber
    Dreaming dreams no mortal dares to dream

    The birches sigh and moan like lover’s cries
    Wrapped tight in their blanket of pristine snow

    I tread the forest with a light step, an intruder here
    The wind erasing my existence as I pass unnoticed

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