Ferns are seedless plants that possess a developed vascular system. The true ferns have complexleaves (megaphylls) that contain more than one vein.
This developed system allows ferns to exist in different terrestrial environments. For instance, the extensive rhizome of ferns makes them capable to extract nutrients and water over a large area.
Since bryophytes have no vascular system they are not capable to transport the water and nutrients from one part of the plant to another. Therefore, bryophytes are found in moist environments and not in extreme environments (deserts, tops of the mountains, arctic environment,etc.).
The vascular system of gymnosperms is more complex than the one of ferns. While ferns need external water for fertilization, gymnosperms fertilize the ovule through a pollen tube.