In bryophytes, the sporophyte is a simple unbranched structure with a single spore-forming organ (sporangium). Inside the sporangium, haploid spores are produced by meiosis. Upon germination, a new haploid mycelium or sporangium is formed. These zoospores form in plurilocular sporangium, and can mature into the sporophyte phase immediately. Each sporangium produces a single tube to discharge spores. Many leptosporangiate ferns have an annulus around the sporangium, which ejects the spores. When conditions improve the zygosporangium germinates, undergoes meiosis and produces a sporangium, which releases spores. When conditions improve, however, they germinate to produce a sporangium or vegetative hyphae. In bryophytes, the sporophytes are always unbranched and produce a single sporangium (spore producing capsule). This results in diploid and haploid nuclei being found in the germ sporangium. Each branch ended in a sporangium or spore-bearing capsule. Diploid structures include&colon; the foot, the seta, the sporangium, and the operculum. The zygote bearing host cells divide, forming eventually the walls of a new winter sporangium. The globules migrate to the columella when the sporangium is formed. An extension of the sporangiophore called the columella protrudes into the sporangium.