The Class Ustilaginomycetes is a group of fungi commonly known as smut fungi, which are primarily plant pathogens. They infect grasses and cereals, often producing dark, powdery spore masses on leaves, stems, or flowers. Ustilaginomycetes have a biotrophic lifestyle, meaning they derive nutrients from living host tissue, and they reproduce via both sexual and asexual spores. Ecologically and economically, they are significant because they can reduce crop yields, but some species are also studied for their potential in biotechnology and biofuel production.