Those fungi that lack a known sexual reproduction cycle are in the division Deuteromycetes. As far as we know, these fungi reproduce only by an asexual process. (When such an organism’s sexual stage is discovered, the fungus is usually reclassified.)

Many human pathogens are currently in this division. These organisms reproduce by fragmenting, with hyphae segments commonly blown about in dust by air currents and the wind. A familiar deuteromycete is the athlete’s-foot fungus, which can be picked up from fragments on towels and shower-room floors.