ELI5 Talking Grass - Why does the smell of freshly mowed grass release chemicals to warn of oncoming danger?

Did you know that the smell of freshly mowed grass is chemically warning other grass of oncoming danger? Why is this the case? Especially since there is nothing grass can do in response?   ... We explain like i'm five!   Thank you to the r/explainlikeimfive community, and specifically the following reddit users whose questions and responses formed the basis of this conversation: fantheories101, cardboard-cutout, rawseeds, coconut-telegraph, concise_pirate, epistatic & foxmetropolis   To the ELI5 community that has supported us so far, thanks for all your feedback and comments. Join us on Facebook: https://www.facebook.com/eli5ThePodcast/  or send us an e-mail: [email protected] ... we love hearing from you!