A friend of mine recently posted a remarkable picture in his blog (The Magical Mundane) which sparked a number of thoughts and questions in my head. Of the many questions I had, a recurring one was whether plants/trees had emotions. It seemed like the image of this beautiful tree in my friend’s blog was able to convey emotions and feelings. I decided to look into this out of my own interest and also because I was once told of an interesting experiment in which a plant detected distress and subsequently reacted in a negative manner.
The first record of the plant emotion/perception phenomena dates back to the middle of the 19th century when German scientist, Dr. Gustav Theodor Fechner, initially proposed the idea. Shortly after, the first experiments were conducted by one of India’s great scientists, Sir Jagadis Chandra Bose. Bose used his own invention of a crescograph (which detects the growth of plants by magnifications of up to 10,000 times) to show that plants responded to various stimuli (eg. tin, chloroform) by slowing down and even halting their own growth. Bose even took to razoring and stabbing parts of plants with sharp instruments which resulted in the plants reacting negatively and subsequently dying. Bose, who also invented the resonant cardiograph, recorded pulsations within living organisms using this contraption. He demonstrated that both plants and animals responded similarly on a resonant cardiograph when subjected to various stimuli. As a result of what he witnessed, he said that “everything in man had been foreshadowed in the plant”, and proposed “experimentation on vegetation would contribute to the lessening of animal and human suffering”. Additionally, Bose came up with the idea that plants possessed a circulatory system where their sap represented the blood of animals (2).
In the 20th century, American scientist, Cleve Backster, justified the use of a lie detector test (polygraph) for use on plants stating that polygraphs measured electrical resistance and water had the ability to change electrical resistance in leaves. Backster recorded the polygraph readings of plants to be initially similar to that of humans subjected to a polygraph test. Subsequently, in one unplanned incident, Backster burnt a leaf of one plant which caused a peak in the tracing patterns of another plant that was connected to a polygraph. Backster claimed that this action somehow “inspired fear” in the other plant. Whilst being ridiculed by the scientific community, Backster continued to perform additional experiments still believing the notion of plants and trees being able to experience emotions.
Several years later, Horowitz et al. (1975) published an article in the peer-reviewed journal, Science, as a follow-up of Backster’s earlier work involving brine-shrimp and plants. Their experiments involved repeating Backster’s brine-shrimp-water boiling experiment but with greater accuracy. The aim was to determine whether there was any communication between plants and animals. The researchers measured electrical activity using a polygraph from the leaves of a Philodendron plant while injecting micropipettes filled with live brine-shrimp (or distilled water as a negative control) into boiling water. The results of their experiment revealed no such evidence of perception in plants (3).
There have been a couple of publications since the work of Horowitz et al. which have considered the effect of external stimuli on plants and have delved into the molecular mechanisms of plants and plant signalling. These publications, whilst being scientifically-accepted, do not look to answer the question of plants expressing emotions.
An interesting publication which I came across while looking at the topic of emotions in plants was one I couldn’t avoid mentioning is this post: an experiment was peformed whereby Viagra was added to a vase of flowers. The researcher was interested in determining whether Viagra would increase the shelf-life of flowers in a vase. She treated flowers with 1 mg of Viagra dissolved in water (50 times less than the amount required to treat erectile dysfunction in men) and found the flowers lasted a week longer than a control bunch. This paper states that Viagra had also been tested on strawberries, legumes, roses, carnation, brocolli and other perishables (4). From my experience, adding sugar helps…to the flowers that is.
Since the above studies, there have been experiments performed to decipher plant emotions. However as there is no objective method to meaure plant emotions, these works cannot be peer-reviewed and consequently fall into the basket of pseudo-science. In spite of this, amongst the community of people who regard plant emotions as a fallacy, there is a community of people who believe otherwise i.e. giving plants or trees nurture, attention and care is of benefit and encourages their growth. Personally, I don’t believe that peer-review is the be-all and end-all of science. I do practise my science ethically when I am in the lab but I think its fine to be open to new ideas. As this type of science is subjective, I don’t think it precludes the observations and results of its forefathers as being untrue.
(2) Autobiography of a Yogi by Paramahansa Yogananda (1946)
(3) Horowitz KA, Lewis DC and Gasteiger EL (1975). Plant “Primary Perception”: Electrophysiological Unresponsiveness to Brine Shrimp Killing. Science 189: 478-480
(4) Siegel-Itzkovich J (1999). Viagra makes flowers stand up straight. BMJ 319: 274
6 years ago