Wild tobacco plants evolved tobacco as a defense mechanism. Tobacco paralyzes most insects after ingestion which keeps it from being devoured and helps it survive where it grows best, which is in the desert surprisingly. Various insects are immune to the paralysis caused by ingesting tobacco, insects like the hornworm caterpillar. The tobacco plant sends off chemical signals when it is under attack from an insect, signals to nearby tobacco plants to alert those other plants of the predator which is devouring it, but also to nearby insects which want to eat the insect consuming the tobacco plant. Not all plants have developed such a robust mechanism of defense like paralysis but all plants have a chemical S.O.S system, and this mechanism has the scent of fresh flowers and fresh cut grass to human beings. This is why freshly cut flowers and freshly cut grass smells as it does. This biological marker mimics tobacco in that it serves as a warning signal to nearby plants and as a dinner invite for insects to eat other insects. The reason plants are so effective when calling the right predator for reinforcement is because the plant uses the saliva of the insect devouring it, a resource which is left over during consumption. Plants can break down the compounds within the saliva of insects and figure out exactly which insect is eating it so that the correct chemical marker is sent out