The name of Fusarium comes from Latin fusus, meaning a spindle. Fusarium is a large genus of filamentous fungi, part of a group often referred to as hyphomycetes, widely distributed in soil and associated with plants. Most species are harmless saprobes, and are relatively abundant members of the soil microbial community. Some species produce mycotoxins in cereal crops that can affect human and animal health if they enter the food chain. The main toxins produced by these Fusarium species are fumonisins and trichothecenes. While most species are considered harmless, some Fusarium species and subspecific groups are among the most important fungal pathogens of plants and animals. The taxonomy of the genus is complex and phylogenetic studies indicate seven major clades within the genus. The genus Fusarium comprises at least 300 phylogenetically distinct species and 20 species complexes.