Figure 4. Cleistothecia of Microsphaera spp.: a) Light micrograph of a Microsphaera sp. cleistothecium broken open to show several transparent saclike asci containing oval ascospores. Notice how the tips of the appendages are dichotomously branched. (Courtesy R. Wick) b) Scanning electron micrograph (500X) of a cleistothecium of Microsphaera alni. In this close-up view you can easily see the dichotomous branching at the tips of the cleistothecial appendages. (Courtesy M.F. Brown and H.G. Broztman)