Plant cells have indigestible cell walls. Often, using microscopic examination, the food plant from which the cells originated can be identified. This manual describes how to detect most of the common food plants, with the exception of starches such as potato, wheat, and rice. The plant cells featured in this manual, because they have been subjected to chewing and swallowing in the digestive process, are not identical with plant cells pictured in standard texts. The manual provides advice on the supplies needed, how to prepare slides, the microscopic examination of slides, the use of a dichotomous key to identify materials, and scanning electron microscopy of plant foods commonly found in stomach contents. Also included is the key to plant foods commonly found in stomach contents. Glossary and appended details of procedures and formulas for solutions discussed in the body of the report.