The order Hysteriales is a small group of fungi within the class Dothideomycetes, primarily characterized by their distinctive elongated, slit-like fruiting bodies (ascomata), often appearing dark and carbonaceous. These fungi are mostly saprobic, growing on decaying plant material, though some are weak pathogens on plants. Their asci are bitunicate (having a double wall) and produce ascospores that are usually hyaline to dark, septate, and sometimes thick-walled. Hysteriales are notable for their adaptation to dry environments, with many species found on bark, stems, and twigs. Morphologically, they are recognized by their long, narrow hysterothecia, which open by a longitudinal slit to release spores, distinguishing them from other Dothideomycetes.