Smuts are ubiquitous, type I allergens that are parasitic plant pathogens, which require a living host to complete their life cycle, and are not usually found growing indoors. Smuts are most often found on corn, grass, weeds, flowering plants and other fungi; they are usually disseminated by wind. They are called smuts because they form black powdery spore masses that resemble soot or smut. Smuts are indistinguishable from Myxomycetes and Periconia under 600x microscopy.