Chemical Warfare Arsenal

A plant cannot run, so it fights with chemistry. A single species can make hundreds of defensive compounds — alkaloids, terpenes, phenolics, and cyanogenic glycosides built to poison, repel, or disable almost anything that tries to eat it.

Caffeine is a natural insecticide. Coffee plants produce it to paralyze insects that feed on their leaves. Nicotine, another insecticide, paralyzes the nervous systems of herbivorous insects. Humans simply co-opted these plant weapons for their psychoactive side effects.