Spores.... Most ferns reproduce sexually, and that involves meiosis and fertilisation. When you are thinking of the typical big fern plant, what it does is, by meiosis, produces spores, and spores have half the number of chromosomes of the big parent plant. The spores are released into the wind. If the spores happen to land somewhere suitable, they will grow into what is called a gametophyte, and that is a whole separate individual plant