Asked by: Lucy Brooks, Harrogate
You are smelling a mixture of oxygenated hydrocarbons that include methanol, ethanol, acetaldehyde and acetone, called green leaf volatiles (GLV). We like the smell because we have come to associate it with summer and weekends.
The smell isn’t just an accidental by-product of the cut leaves, however. There is some evidence that plants deliberately emit volatile compounds in response to damage. Wild tobacco plants, for example, emit a certain GLV only when they are being grazed by caterpillars. This acts as a signal to attract nearby bugs that prey on the caterpillars.