There's so much I've read about whilst researching this topic that has left me fascinated and intrigued, I couldn't fit it all into one post! So here's the next part, which takes us into how plants and trees communicate, and respond to emotion and stimuli.
COMMUNICATION
Trees and plants can't talk in a verbal sense as we do, and can't run from a perceived threat, but it seems perhaps they sense them, feel them, and respond in their own manner.
It seems they do communicate also, and inform the other members of their "communities" of possible threats, or conditions not conducive to their wellbeing.
In a fascinating article I read in Smithsonian Magazine, Peter Wohlleben, author of "The Hidden Life of Trees: What they feel, How they Communicate" states: “All the trees here, and in every forest that is not too damaged, are connected to each other through underground fungal networks. Trees share water and nutrients through the networks, and also use them to communicate. They send distress signals about drought and disease, for example, or insect attacks, and other trees alter their behavior when they receive these messages.”
These connections between trees are called mychorrizal networks- Wohlleben also refers to them as "the wood-wide web" (a charming analogy, I think!). The root tips of trees have a symbiotic relationship with tiny fungal filaments, and these form the basic network links. Over time the roots connect (with the help of those fungal filaments) with the roots of other "allied" trees, thus expanding the network.
To communicate, trees send chemical, hormonal, and slow-pulsing electrical signals through the network. A researcher at the University of Lausanne (Switzerland) has been studying the electrical pulses, and has actually identified a voltage-based signaling system of a very similar voltage to that of animal nervous systems.
Trees also communicate through the air, which brings me to one of my favourite examples in this section. I read about this in the same Smithsonian article, and it comes from Sub-Saharan Africa, where the umbrella thorn Acacia is very common.
When a giraffe starts chewing on acacia leaves, the tree notices this, and sends a distress signal in the form of ethylene gas. When other acacias detect this gas, they start increasing the amount of tannins in their leaves. Tannins render the leaves bitter and unpalatable to animals, and can be toxic to some of them in large doses.
Giraffes seem to be aware of this though, as they've evolved alongside acacias. Thus they browse into the wind, so the "warning gas" doesn't reach trees ahead of them. If there's no wind, a giraffe will walk around 100 yards- further than the gas can travel in still air- before browsing on other acacias. I can't help but agree with what the article says here- "perhaps giraffes know that the trees can talk to each other"..
Plant roots form the same type of communication network as trees do, through symbiotic relationships with bacteria and fungi, and links to other plant roots - these are called mycelial networks. In some instances, plants can be part of a mycelial network that can extend over miles..that's one very big "brain"!
This mycelial network can connect all plants in a particular area into one whole, and enable them to communicate. If plants in the network detect that another plant is ill, those able to do so send helpful compounds through the network to where they are required. Plants and trees seem to help other members of their "families" and their species, and members of other species too throughout their lives..just as we do!
In fact, plants and trees seem to show many of the same behaviours that we do; they have a means of communication- a "language", they form families and social groups and nurture those, they adapt to their environments, co-operate with other species..sounds quite familiar, doesn't it?
RESPONSE TO EMOTION AND STIMULI
One of the most fascinating examples I came across relating to this section was another experiment conducted by J.C. (Jagadish) Bose; polymath, physicist, botanist, biologist and archaeologist. He was responsible for some of the earliest work on plant neurobiology, conducted in the early 1900's. Bose experimented by treating plants with a wide variety of chemicals to see what effect could be noted. In one experiment, he covered mature trees with a tent, and then used chloroform on them. The trees "breathed in" the chloroform through their stomata (these are like "pores" in the plant's epidermis), just as they would normally breathe in air. Once they were anesthetized, the trees could be uprooted and moved without going into shock (perhaps landscape gardeners should try this when relocating trees!).
He also found that morphine had the same effects on plants as on humans- it reduced the plant's pulse in proportion to the dose given. Too much brought the plant to the point of death, but the administration of Atropine revived it, as it would humans. Alcohol, he discovered, did indeed get a plant drunk. As it does in us, alcohol induced a state of excitation in the plant early on, but as intake progressed the plant began to get depressed, and with too much it "passed out". It even had a hangover the next day!
No matter which chemical he used, Bose found that the plant responded identically to human beings; the chemicals had the same effect on the plant's nervous system as they would upon our nervous system.
His work shows a fascinating correlation between plant and human response to certain chemical stimuli, I think. There's a couple more interesting examples to be given regarding the response of plants to emotional stimuli too.
In a study done on germinating seeds by Dr. Franklin Loehr, a scientist and Presbyterian minister, several experiments were conducted, with very interesting results. Loehr published these results in 1959 in a book, "The Power of Prayer on Plants".
His objective was to see, in a controlled experiment, what effect prayer might have over living and seemingly "non-living" matter. In the first experiment, three pans of seeds were used- one was the control pan, one pan received positive prayer, and the last received negative or no prayer. Time after time, the plants receiving positive prayer showed faster germination and growth. Those receiving negative or no prayer displayed halted germination and slower growth.
In a related experiment, two bottles of water were purchased. One bottle was used as a control and received no prayer, and a group prayed for the other bottle. The water was then used on two pans of corn seeds, with one pan receiving the "prayer water" and the other receiving the control water. The seeds in the pan that received the prayer water sprouted a day earlier than the seeds in the other pan, and had a higher growth rate. This experiment was repeated many times, and showed similar results with each repetition.
It seems plants respond to other types of emotional stimuli too- such as music..
In the vineyards of the De Morgenzon farm in South Africa, the owner plays music by Bach, Corelli, and Albinoni throughout the vineyards..for the grape vines!
According to the owner, his vines respond to a particular type of music- rock, pop, jazz, rap and techno don't have the same effect. How does he know? Because apparently the vines grow more vigorously and look healthier when classical music is played to them!
His claim has some scientific support too- in 2007, researchers at South Korea's National Institute of Agricultural Biotechnology found classical music triggered a response in two specific genes in rice plants. In the same year, researchers at Trakya University in Turkey found that "relaxing, calming, mentally invigorating" music had a positive effect on root growth in onions during the germination phase.
Plants are perhaps classical music fans, it seems!
In summary, does any of what I've related prove absolutely that plants and trees possess consciousness? No. It does show awareness and intelligence, I think, but does awareness and intelligence indicate or prove consciousness? Is it an indicator in human beings or in animals? Should it be an indicator in plants, as it seems they perhaps possess quite a decent level of it? I guess it depends on how much we're willing to consider.
The concept of mind and brain, and whether or not they exist independently of one another, is one of the arguments at the core of the "hard problem" of consciousness in philosophy, and has been debated for centuries.
I recently read a fantastic article that raised the concept of "brain chauvinism" too, along with a fantastic thought..We can identify with the qualities and behaviours that some animals display as being similar to our own, and therefore we may find it easier to consider the possibility that animals are conscious..but how much do we really stop to consider the concept that other living things- those with no actual organ we can visually identify as being a brain- may be conscious too?
Plants and trees do seem to possess both a mind and a brain, as we do..so does that make them conscious? Nobody can say for sure until we can objectively define consciousness, and until we can capably consider other species as being possibly conscious too!
It seems we mostly define consciousness in basic terms- dictionary terms- that we are aware of our external environment, and are also self-aware. An external, and internal, process of analysis, and of subsequent reaction and response. From what I've read, and thus related to you, it seems that perhaps plants and trees may use similar processes to ours..it's sure made me think twice about how I look at them, and whether or not they may be conscious..
With that said, I'm off to water my garden.
Feel free to share your thoughts in comments!