Notice that the egg is retained in the archegonium, fertilization takes place in the archegonium, sporophyte grows out of the gametophyte. But the Gametophyte is only a few mm across while the sporophyte is quite large. The reverse of the situation in moss and liverworts. Dispersal is by spore. Notice the presence of cones, male and female, for the production of gametes.
Fertilization takes place inside the sporophyte which is retaining the gametophyte.
The embryo of the next sporophyte generation is retained in tissue of 2n sporophyte origin. We now have a sporophyte in the sporophyte. We have gone from a. large gametophyte small sporophyte, to b. large sporophyte and free living small gametophyte, to c. really small gametophyte retained within the sporophyte.