Herbalists should keep safety above any other consideration when using medicinal herbs. This unit provides a firm foundation in plant chemistry from a clinical viewpoint. Identification of herbs is important to avoid collection or purchase of inappropriate plants, adulteration, substitution and possible toxicity. We will explore  how and why plants make secondary constituents, and how to study the plant itself to learn more about its constituents.  Herbal pharmacology include the major classes of herb constituents and, where appropriate, their general effects on mammalian systems.  Finally, manufacture of herbal medicines is reviewed as well as quality control and regulatory issues that influence medicinal safety and efficacy.