The vegetable world comprises three main groups of plants: superior, intermediary and inferior. These encompass bacteria, microscopic algae, mushrooms, ferns, brushes and trees, among others. Their identification is a task of specialists and the limit between the vegetal and animal world is not clear. Books about medicinal properties of vegetables normally seem to treat differently herbs and medicinal plants. However, herbs are seed producing annual, biennial or perennial plants that do not develop a persistent woody tissue. Perhaps because herbs have such an important historical and tradition in healing, sometimes they are treated as a special category of plants i.e., those particularly valued for their medicinal, savory or aromatic qualities.

In the "Herb Finder", herbs are considered as medicinal plants and taken only for their medicinal or aromatic properties. Since the traditional or popular name of medicinal plants varies so much according to regional and cultural aspects, they have been grouped alphabetically according to their most common English name.