Phytochemistry isolates and identifies the specific chemical compounds a plant produces, alkaloids, glycosides, terpenes and essential oils among them, using extraction and instrumental analysis to say precisely what a plant contains rather than relying on its traditional name or appearance. As postwar organic chemistry turned increasingly toward natural products, the field gained its own dedicated journal, Phytochemistry, whose first volume appeared from Pergamon Press in 1961 under the founding editorship of Tony Swain and Jeffrey Harborne, giving plant chemical research a home separate from general botany and pharmacology, alongside the founding of the Phytochemical Society itself.
Every tradition that burns, drinks, chews or offers a named plant for its effect, incense resin, a ritual infusion, an entheogenic mushroom or vine, is making an implicit chemical claim, and phytochemistry is what can confirm or correct it by identifying the actual active compound and its physiological action. The atlas relies on phytochemical findings wherever a ritual plant's effect is described, distinguishing a chemically documented action from an effect a tradition attributes to the plant on other grounds.