What are ferns? Can you tell them clearly?

Pteris tremella, also known as Pteris tremella and Pteris tremella. It is a variety of Nostoc flagelliforme of Pteris and Pteris. Pteridophytes in China are mainly distributed in the south of the Yangtze River, such as Selaginella, Vitex negundo, Celastrus angulatus, Dryopteris breviscapus, Pteris venus, Pteridophyte, Rhizoma Cibotii, Rhizoma Osmundae and Nephropteris. Generally, they are terrestrial, the epiphytic ferns are oak, Parthenocissus tricuspidata, and the aquatic ferns are Azolla. The vast majority of existing pteridophytes are herbs, but there are also some woody species, such as the small iron tree Solo, which is the main tree species in the forest during the dinosaur era and also an important food for dinosaurs.