The little dots collected from under the fern leaves are spores, not seeds. Ferns are different from seed-bearing plants in that ferns in a sexless way through sporophyte generation. Spores dropped from or taken from grown fern leaves have developed prothallium. Each prothallium generates male and female organs in what is called the gametophyte stage. When fertilization of the female gametophyte happens, small fern plants or leaflets start to grow.