Sunflowers co-operate to share fertile patches of soil

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Sunflower by Mike Robinson

This article is not so much about the animal to human relationship but a reminder that plants behave in a more socially responsible way than humans sometimes. That may surprise a lot of people. However, research indicates that sunflowers co-operate to share fertile patches of soil. In other words, sunflowers demonstrate a kind of “vegetative egalitarianism”.

Sunflower by Mike Robinson

Sunflower by Mike Robinson

If two sunflowers are living close to each other and one of the sunflowers detects, through its roots, a nutrient rich patch of soil then the roots migrate towards that area but one sunflower will restrict the amount of roots that go into that patch of fertile soil to allow another sunflower nearby to share in the nutrients available. It is a sophisticated example of mutual cooperation in a kind of plant society.

There appears to be a growing body of knowledge that plants do not necessarily behave in an entirely solitary manner.

“We need to recognise that plants not only sense whether it’s light or dark or if they been touched, but also whom they are interacting with.”-Susan Dudley, a plant evolutionary ecologist at McMaster University in Hamilton, Canada, in discussing the matter with Science in January.

Scientists in China have discovered that rice plants do better when they grow alongside their “kin”. This allows farmers to boost crop yields. It also appears to be an example of plants gaining a sense of well-being when growing next to plants of the same species.

In a further study, regarding a family of small weeds (Arabidopsis), the researchers found that when the plants grow next to each other (i.e. next to close relatives) they shifted the arrangement of their leaves to avoid placing the neighbour’s leaves in the shade. They did not do this when neighbouring leaves were not those of close relatives. The researchers have not understood yet how the plants are able to recognise “close relatives”.

Scientists have also discovered that warning signals are sent out by plants to other plants in a community when there is danger about. When a giraffe eats an acacia, for instance, the tree begins to pump out ethylene gas. The surrounding trees pick up this gas and transfer unpleasant tasting tannins into their leaves.

Finally, you may have read about how trees can ‘talk to each other’ through fungi which grows on their roots. The trees form an underground social network. They discovered that fungi sends out superfine threads known as hyphae that weave into the tree roots. This creates “an interface through which molecular transmission might occur”.

The network allows the roots of trees of different species to share resources and also issue warnings about harmful parasites in the area. We need to respect tress more and stop cutting them down for toilet paper and burning them to clear the land for plantations.