On the underside of the pinnae is the reproductive system in the form of thick sori filled sporangia without indusium.
A sporangium has a structure and functions similar to those of the uterus of mammals. Each of the sporangia that form a sorus is attached to the surface of a pinna with a kind of umbilical cord called sporangiophores, which is nothing more than a hollow tube of cells, where the sporangia gets the nutrients it provides the pinna.
The nutrients pass into the ring of cells that serves as the placenta and embraces the spores contained in a transparent membrane in a pouch. Spores receiving nutrients through the ring and mature. Meanwhile, the ring, as well as a uterus surrounding the spores and feed as a placenta, accumulating power and standing in tension. When at last the spores are ripe and the fern detects that the conditions of humidity and temperature, the ring is displayed as a catapult with unusual force, the membrane of the bag is torn and the spores are thrown as far as possible , at the mercy of wind and water to find an ideal location for germination.
The spores that manage to fall into a small crack in a coastal rock containing a small amount of substrate, they germinate and, after the union of gametes, the birth of a new fern love the sea.