Gabby Gardens and Wordy Woodlands – How Plants Communicate With Each Other

Today, I’ll discuss how plants communicate with each other – and boy, do they have a lot to say.

Naturally, plants don’t “talk” to each other in the same manner as humans do, but they nevertheless actively communicate with each other in a variety of ways. How?

Through chemicals in their roots – Scientists have so far discovered that plants produce over 100,000 different chemicals, called root exudates, in their root systems which send a variety of signals to other plants. The small hair-like structures we see on each plant’s root system form interconnections with other plants, creating what is known as a This rhizosphere may be only a few meters wide in a small garden. However, in larger gardens and forests, this rhizosphere may reach thousands of square acres. In essence, each rhizosphere functions as the community chat room for all neighboring plants.
Through chemicals they emit from their roots and leaves – These chemicals, referred to as volatile organic compounds (VOCs), are chemically related to pheromones used by animals and function in similar ways to either attract, repel, or warn other plants of changes to the environment.
Through sound signals – We already know that plants react to music and human voices via sound vibrations and respond differently to various frequencies. However, they also send sound signals to other plants – and even animals – in frequencies that cannot be heard by human ears.

So, what do plants communicate?

Plants let other plants know who they are. While scientists are still unsure of the exact mechanism of root exudate identification, they do know that plants are able to recognize identical plant species (podmates, – offspring or siblings of the original plant), similar plants which may be close relatives, and plants which are foreign to them.
Plants communicate friendship and hostility of other plants – If a plant recognizes another plant as a podmate or another similar species, plants alter their root system to produce more shallow roots with intertwined rhizome branches which not only nourish related plants, but also maximize space for podmate plant growth. On the other hand, if a plant identifies another plant as a stranger or hostile species, the plant will grow a deeper, longer, and more extensive root system in an effort to reduce available nutrients to the offending plant so that it is either weakened or dies.
Plants communicate friendship or hostility of non-plant visitors – We have already discussed how a Sensitive Plant (Mimosa pudica) responds to touch. But not only does the initial plant react to tactile stimulation, it also emits a chemical messenger to other nearby Mimosas to be on high alert. Similarly, if predatory insects, such as a hungry beetle or aphids, start to attack a plant for their next meal, the plant will send out chemical signals through its leaves and roots to warn other plants of the assault. Also, it may emit VOCs into the leaves, the atmosphere, or even the soil which function to repel or kill the predator(s).
Plants alter the soil – Like all living things, plants are in constant states of communication and feedback with their environment. If a plant senses it is growing in soil which is not conducive to its growth or survival, it may send out root exudates to make the soil’s chemical composition or structure more supportive of its growth, or even alter the soil to make it less hospitable for competing plants.
Plants alter their growth patterns – Did you know there is such a thing as
“crown shyness?” Next time you are in a forest or a gathering of trees, look up. You will probably see the crowns of some fully mature trees which do not touch each other. Instead, they form a canopy of channel-like gaps. This phenomenon is most common between the trees of the same or similar species, but sometimes can also be seen in mixed forests. While scientists are not sure why this occurs, they believe this is an adaptive behavior intended to inhibit the spread of leaf-eating insects and their larvae.