Rhizopus stolonifer (black bread mold) is a widely distributed Mucoralean mold.
Asexual spores are formed within sporangia, which break to release the spores mature. Germination of these spores forms the haploid hyphae of a new mycelium. R. stolonifer grows rapidly at temperatures between 15 and 30 degrees C.
Rhizopus stolonifer is a heterotrophic species (Schipper 1984), in that sexual reproduction happens only when opposite mating types (designated + and -) come in contact. Successful mating results in the formation of durable zygospores at the point of contact. Subsequently, the zygospore germinates and forms a sporangiophore whose sporangium contains both + and - haploid spores.
There are three varieties: R. stolonifer var. stolonifer produces straight, erect sporangiophores, whereas those of R. stolonifer var. lyococcos are curved . A closely related species, Rhizopus sexualis, differs primarily in being homothallic (self-compatible).