You’ll never cut your grass again without thinking of this weird fact – grass cries for help when it’s mowed. No, you can’t hear it, but scientists have discovered grass screams when cut.
How does grass scream when cut?
We’re only just beginning to understand how plants communicate with one another and the rest of the world around them (including insects).
Dr. Michael Kolomiets, a Texas A&M AgriLife Research plant pathologist, published an article in 2014 in The Plant Journal noting that the aroma of cut grass is the plant’s way of both signaling distress and attracting beneficial insects that will help it heal.
According to ScienceDaily (cited below): “When there is need for protection, the plant signals the environment via the emission of volatile organic compounds, which are recognized as a feeding queue for parasitic wasps to come to the plant that is being eaten and lay eggs in the pest insect,” Kolomiets said.
Grass produces a “defensive” protein when damaged. Of course, that doesn’t stop the lawnmower or insects from destroying the blades. But it appears to produce a compound that repels insects that are feeding on the damaged grass.
This compound, or one related to it, also appears to attract organisms like parasitic wasps that feed on insects like caterpillars that are destroying the grass.
Or to put it in science-speak:
“We have proven that when you delete these volatiles, parasitic wasps are no longer attracted to that plant,even when an insect chews on the leaf. So this volatile is required to attract parasitoids. We have provided genetic evidence that green leafy volatiles have this dual function — in the plant they activate production of insecticidal compounds, but also they have indirect defense capability because they send an SOS-type signal that results in attraction of parasitic wasps.”
So, maybe it’s not so much that grass screams when cut so much as it cries for help. Either way, freshly cut grass emits a compound that repels damaging insects and attracts insects with a protective function.
It’s just one of the many ways that plants are far more complex than we had ever previously imagined. — WTF fun facts
Source: “Mown grass smell sends SOS for help in resisting insect attacks” — ScienceDaily