Updated: Mar 25, 2020
Nicotine (C10H14N2) in its natural form is a parasympathomimetic substance (stimulant or cholinergic drug) produced in many plants throughout the Solanaceae (Deadly Nightshade) family. The most well-known to produce this alkaloid are in the Nicotiana genus, containing the "tobacco plant," species Nicotiana Tabacum. Nicotine can also be found in small quantities in tomatoes, potatoes, eggplant, bell peppers and even the coca plant.
It is thought the stimulating effects from nicotine deter insects and other herbivores from eating these plants by speeding up their bodily functions to the point the organism experiences negative side effects or die. Although minuscule levels are found in many plants, the Nicotiana Tabacum species contains the highest concentration of up to 5% nicotine by weight. This is equivalent to about 22 grams per pound.