Latest research reveals extraordinary findings
Most people know plants as living organisms, but don’t realise just how complex they are. Like humans, plants and trees face challenges such as predators, limited food availability and extreme temperatures. However, without being able to move, they have developed other mechanisms to adapt to threats.
New research from the University of Canterbury and published in The Conversation https://theconversation.com/the-secret-sensory-life-of-plants-researchers-are-discovering-how-they-see-hear-feel-and-even-remember-277076 shows that plants have a sophistication that allows them to detect and adjust to environmental signals.
The research, which builds on a growing field of study, shows plants are able to perceive light, respond to touch, detect sound – and even retain memories through changes in their DNA.
Research shows that photoreceptors in plants have a light absorbing chromophore. When light hits, the chromophore shape changes, activating the photoreceptor. This photoreceptor acts like a switch which activates proteins, activating other processes and responses.
Some of these processes are well known, such as plants growing towards light, or sunflowers turning towards the sun, but new research suggests that plants, specifically trees, can actually detect the summer solstice. This is beneficial for plants in colder climates, as they have been found to slow down new cell generation and focus on incomplete cells before winter. Low temperatures can damage incomplete cells, making them useless.
Maybe the most well-known example of plants sensing touch is The Venus Fly Trap (Dionaea muscipula) which has small sensory hairs that allows it to detect prey. If there are two touches of hairs in a short time period (roughly 30 seconds), this movement is converted into an electrical signal allowing for the plant to close. However, a recent study out of the University of Zurich https://journals.plos.org/plosbiology/article?id=10.1371/journal.pbio.3000740 has shown that only one touch may be necessary – indicating that the plants are adapting to their prey movements over time.
Being able to listen has also allowed plants to cleverly counter predators. How they listen, however, is quite different to how humans do. Plants can detect the vibrations of herbivores eating the plant and this activates defence mechanisms such as the use of chemicals https://pmc.ncbi.nlm.nih.gov/articles/PMC4102826/ . Plants can produce hydrogen peroxide which acts as a deterrent for insects attempting to feed.
The University of Missouri research found that vibrations that are detected can also be differentiated by plants https://pmc.ncbi.nlm.nih.gov/articles/PMC4102826/. It appears that plants can tell the difference between insects trying to eat them, the wind or even other animal noises. However, this sense is easily impacted by humans. Researchers in Ghent, Belgium in a 2023 article https://www.sciencedirect.com/science/article/pii/S1360138523000833 have found that noise pollution can impact plants' ability to perceive some of this key information. It was also shown that plants operate within set sound frequencies and intensities, and sounds outside of these ranges, such as highways or industrial noise, may have a negative impact.
The research at the University of Canterbury by Samarth Kulshrestha (2024) focuses on how plants detect the passage of time as part of their seasonal cycle. They found, by studying the European beech, that there is a ‘celestial cue’ that ‘occurs simultaneously across the entire hemisphere (as) the longest day – the summer solstice’. The beech abruptly opened its temperature-sensing window on the solstice, with widely separated populations all starting to respond to weather signals in the same week. It summarised this research by stating: ‘This celestial “starting gun” generates ecological events with high spatial synchrony across the continent.’
Andrew Hacket-Pain from the University of Liverpool (2025) https://theconversation.com/could-trees-know-when-the-summer-solstice-is-259309 says the "solstice acts as a seasonal marker", for all Beech trees, allowing them to maximise reproduction through synchronisation. This could be masting, a burst of reproduction and seed release, or a year with little reproduction if the conditions aren't optimal.
It appears that memories are not just the domain of animal species. As observed in humans, plant memories are stored through epigenetic mechanisms – chemical changes to DNA that don’t affect the genetic code.
This can be greatly beneficial to plants facing stresses such as drought or low nutrient levels. The plant's memory allows for them to adapt more quickly if the same stressor has been experienced in the past or even remember when solstice approximately is.
A major conclusion – plants are highly complex and unique and there is definitely still much to uncover in the future.
Article by Finnegan O'Hara
Photo by Cátia Matos https://www.pexels.com/photo/yellow-petaled-flower-in-close-up-photography-1026232/