Pleospora herbarum. This photograph shows asci of Pleospora herbarum in a slide preparation mounted in erythrosin in ammonia, and viewed with differential interference contrast microscopy. Each ascus contains eight brown spores, and each spore is multicellular, with transverse and longitudinal cell walls, but with one main central dividing wall. The remaining protoplasm in the ascus has stained pink in the erythrosin. Note how thick the ascus walls are: these asci have two functional wall layers. Note also the thin ascus apex so characteristic of the Pleosporales and other ascomycetes with two-layered asci. 1990.
