How can a plant remember anything, we might wonder? One way is that it may have specific chemicals circulating in its system. Calcium, according to a recent discovery, turns out to be the element that prompts Venus flytraps to shut their traps on insects—but only on the second try:
A Venus flytrap’s short-term “memory” can last about 30 seconds. If an insect taps the plant’s sensitive hairs only once, the trap remains still. But if the insect taps again within about half a minute, the carnivorous plant’s leaves snap shut, ensnaring its prey.Curtis Segarra, “How Venus flytraps store short-term ‘memories’ of prey” at ScienceNews
The Venus’s trap is more complex than a mousetrap because the plant can’t just clamp down on any stimulus (bark bits, leaf detritus) without wrecking its sensitive traps; it survives on unwary insects. So, as Suda et al. explain,
Plants have evolved a variety of mechanisms that ‘remember’ external stimuli as part of numerous processes, including acclimation to harsh environments, systemic acquired resistance to pathogens and vernalization. In the short-term memory system of Dionaea (Fig. 1a), the second stimulus can be to any of the leaf ’s six sensory hairs (Fig. 1b), regardless of which hair received the first stimulus. Previous studies showed that mechanical stimulation of a sensory hair generates action potentials that propagate to both lobes of the leaf.– Suda, H., Mano, H., Toyota, M. et al. Calcium dynamics during trap closure visualized in transgenic Venus flytrap. Nat. Plants 6, 1219–1224 (2020). https://doi.org/10.1038/s41477-020-00773-1
The paper is open access. A number of questions remain, of course.
Suda et al. also mention vernalization as an example of plant “memory,”citing a 2018 textbook on plant development. Essentially, many plants “remember” when they have been subjected to cold temperatures and they produce fertile seeds only afterwards. Plant biologists think that this memory prevents temperate zone plants from wasting their energy on ill-timed seeding efforts during their first year. The carrot is a good example of such a biennial plant. Carrots sit out their first year growing a huge, fat root, intending to flower and seed the next year. The carrot has an internal memory system for whether winter has happened or not that keeps it on track.
Although a mind is required to work with ideas—as we humans understand them—many natural systems store vast quantities of information by a variety of other means. That includes plants processing information about their experiences. Even plants, it turns out, have histories.
Other stories on how plants make use of information:
Can plants be as smart as animals? Seeking to thrive and grow, plants communicate extensively, without a mind or a brain.
Researchers: Yes, plants have nervous systems too. Not only that but, like mammals, they use glutamate to speed transmission
Scientists: Plants are NOT conscious! No, but why do serious plant scientists even need to make that clear? What has happened? Quite simply, the need to see humans as equivalent to animals has now spread to the need to see us as equivalent to plants.