These guides are for those willing to first familiarize themselves with botanical vocabulary. To use the guides, you follow a key which classifies plants according to structural characteristics such as the number of petals and their arrangement, the number of stamens, placement of the ovary, etc. While illustrations of these features are provided in the books, some knowledge is necessary to use them properly. On the other hand, these books can be much more efficient to use than others such as the Audubon guides that require you to look through many pages to try to find a matching picture. Among Peterson's Field Guides titles for botany are Pacific States Wildflowers, Southwest and Texas Wildflowers, Eastern and Central Edible Wildplants, Mushrooms, Ferns, Eastern Trees, Western Trees, Trees and Shrubs, Eastern Forests, Rocky Mountain Wildflowers, Wildflowers of Northeastern/Northcentral North America, and Medicinal Plants.