About Protonema
A protonema (plural: protonemata) is a thread-like chain of cells that forms the earliest stage of development of the gametophyte (the haploid phase) in the life cycle of mosses. When a moss first grows from a spore, it starts as a germ tube, which lengthens and branches into a filamentous complex known as a protonema, from which a leafy gametophore, the adult form of a gametophyte in bryophytes, grows. Protonemata are filamentous in mosses, thalloid or globose in liverworts, and globose in hornworts.
