为什么新割的草那么好闻

If you grew up in the suburbs, you recognize it immediately: the sweet, sharp smell of someone mowing ¹ a lawn or ballfield. As it wafts ² into your nostrils ³, it somehow manages to smell exactly like the color green. But what are we really smelling when we inhale ⁴ that fresh-cut grass scent ⁵? And why do we like it so much?, ,Chemically speaking, that classic lawn smell is an airborne mix of carbon-based compounds called green leaf volatiles, or GLVs. Plants often release these molecules ⁷ when damaged by insects, infections or mechanical forces -- like a lawn mower ⁸., ,Plants manufacture slightly different forms of GLVs depending on what's happening to them, said Ian Baldwin, a plant ecologist and founding director of the Max Planck Institute for Chemical Ecology in Jena, Germany. In a 2010 study published in the journal Science, he and colleague Silke Allmann, of the University of Amsterdam, found that tobacco leaves punctured ⁹ and rubbed with insect saliva ¹⁰ released a different bouquet ¹¹ of volatile ⁶ compounds than leaves that had been poked ¹² and brushed with water., ,GLVs are small enough to take to the air and float into our nostrils. In some cases, they can be detected more than a mile from the plant where they originated. Other species, such as insects that eat plants and the predators ¹³ that eat those insects, are extremely sensitive to different GLV aromas ¹⁴. For instance, Baldwin and Allmann discovered that predatory Geocoris bugs ¹⁵ are attracted to the GLVs released by plants chewed on by a pest called the tobacco hornworm. In other words, the specific smell of the besieged ¹⁶ plants indicates to the predators that a snack is nearby.