Zygomycetes are mostly terrestrial and live in soil or on decaying organic material. Some form mycorrhizae , mutualistic associations with plant roots. Refer to Campbell, Figure 28.3 for the life cycle of the zygomycete, Rhizopus stolonifer , a common bread mold. The mycelium consists of horizontal hyphae that spread out and penetrate the food source. Sporangia develop at the tips of upright hyphae.
Mitosis produces hundreds of haploid spores that are dispersed through the air.
If they land in a moist, favorable environment, spores germinate into new mycelia. The zygosporangium germinates a sporangium that releases the genetically recombined haploid spores. If they land in a moist, favorable environment, spores germinate into new mycelia. Even though air currents are not a very precise way to disperse spores, Rhizopus releases so many that enough land in hospitable places. Some zygomycetes, however, can actually aim their spores.