Sporangia form a halo around a central, round vesicle at the apex of a sporangiophore. In fungi, a sporangium is produced at the end of a sporangiophore that sheds spores. An extension of the sporangiophore called the columella protrudes into the sporangium. Two sporangia are more or less parallel to the sporangiophore before bifurcation. The asexual fruiting structure (the sporangiophore) of "Pilobolus" species is unique. The name "vasiformis" came from the flask-shape of sporangiophore. The species were differentiated based on the sporangiospore shape, sporangiophore type, and apophyseal shape. Lower temperatures favor zygospore formation and higher temperatures favor sporangiophore production. Sporangia are supported by a large apophysate columella atop a long stalk, the sporangiophore. The sporangium forms on the sporangiophore and contains haploid nuclei and cytoplasm . High humidity increases zygospore formation and low humidity increases sporangiophore formation. In stage II, the sporangiophore develops a sporangium. Although the sporangiophore bears sterile processes, it is not associated with any leafy bracts. The developing sporangiophore grows such that the maturing sporangium is aimed directly at the light. As to "Hamatophyton", each sporangiophore at the strobilar node bifurcates into two parts.