Do you love the smell of freshly-cut grass? If yes, you’re a sadistic bastard because that’s the smell grass emits when it’s being wounded. It’s a stress response, according to research by plant biologist Michael Kolomiets.

Get this: Whenever a plant is under attack (when grass is mowed for example or when pests munch on plant leaves), it sends a sort of “SOS” signal by releasing volatile organic compounds, or that scent of summer that we’re all familiar with, according to a 2014 study cited by Reddit user Nickel62 in a post in Reddit’s Ask Science community.

It’s the plant’s way of “communicating” to the environment that it needs help.

And while we’re attracted to this smell, other herbivore pests may be repelled by it, adds Kolomiets. What’s even more fascinating, though, is these chemicals attract parasitic wasps.

The wasps end up saving the plant by attacking or laying eggs on whatever insect is feasting on the plant, essentially killing the plant’s predators.

African acacias trees have an even more remarkable defense mechanism, mentions Reddit user Skulder.

Whenever the tree is under duress, its leaves fill with poison. Soon after, the tree releases a chemical warning to other acacias to do the same, describes famed biologist David Attenborough in the Private Lives of Plants. Acacias within 50 yards begin producing poison, even if they are not under attack (yet).

If these chemicals are a plant’s way of repelling predators, why do humans love the smell of freshly-cut grass so much? We love it so much, in fact, that perfume makers attempt to imitate it. Yep—grass perfume. This exists.

We’re not really sure why humans love this scent so much, but Reddit user Podorson cites an interesting study published in the Oxford Journal, which found that the “green odor” relieved stress in monkeys.

The odor also helps plants ward off bacterial infections, so maybe we associate it with fresh vegetables that are ripe to eat.