Claviceps belong to ascomycetes. When a fungus reproduces sexually, two haploid hyphae of compatible mating types come together and fuse. In some fungi the fusion of two haploid cells immediately results in diploid cells . However, in other fungi (ascomycetes and basidiomycetes), an intervening dikaryotic stage ( , i.e., two nuclei per cell) occurs; such a condition is called a dikaryon and the phase is called dikaryophase of fungus. Later, the parental nuclei fuse and the cells become diploid). The fungi form fruiting bodies in which reduction division occurs, leading to formation of haploid spores.