Haploid spores grow into cottony tangles of hyphae called mycelia. These mycelia usually grow under the surface until they meet up with another mycelium. The two join (plasmogamy) and produce a series of binucleate, dikaryotic hyphae that reach above the ground and form the fruiting body or basidioma. The cells of the basidioma cannot divide by normal mitosis because they have must produce two daughter cells each with a copy of both parental nuclei. This is accomplished through the formation of a clamp connection.