Sex. In some fungi reproduction is by asexual methods only [i.e., by cell division, spore formation, fission, or budding, without the need for union of cells], in others it is parthenogenetic [by means of an unfertilized gamete], but in most there is a sexual process. Probably more than 1/3 of all fungi have more than one type of reproduction, frequently in two well-marked phases (the "teleomorph" and "anamorph") which may have separate species names.
Fungi having sex organs are commonly monoecious [having both male and female sex organs in the same individual], infrequently dioecious [male and female sex organs in different individuals].... As there is no objective definition of species, for most fungi what constitutes a species for one taxonomic mycologist may be a genus or a variety for another.
-- Ainsworth & Bisby, Dictionary of the Fungi, 7th ed. 1983.