​An introduction to a common group of fungi, the powdery mildew fungi, which are obligate parasites of plants. This exercise can be used to explore the ecology of a diverse group of fungi and/or as a way for students to learn about how fungi are classified. This lesson is suitable for grades 7 -12 and does not require the purchase or maintenance of special cultures, since powdery mildew fungi are easy to find on plants in nature. Teachers and/or students collect leaves infected with powdery mildew fungi from different kinds of plants and examine them with dissecting and compound microscopes. Other simple equipment, such as newspapers, plant press or heavy books, microscope slides, cover slips, and dissecting needles also are needed.

(Note: This lab works best in regions that experience cold weather for part of the year, since this encourages production of cleistothecia (sexual stage). This lab may not work as well in areas where warm weather prevails year-round, since the conidial (asexual) stage of the powdery mildew fungi occurs primarily.)