Each frond of the chain fern is weighed down by the bud at its tip, which can root and grow into a new plant if it touches the ground (2) (4) (5). The chain fern also has creeping rhizomes which create new roots and shoots, enabling the plant to spread (1) (5).
The adult fern, the sporophyte, releases spores from the ‘sori’ on the underside of the leaf, which are seen as brown spheres. The spore, when attached to a suitable substrate, develops into a gametophyte, which is tiny, green and heart-shaped. As it develops, the gametophyte grows both male and female reproductive organs. The male part of the gametophyte releases sperm, which swim towards the haploid egg. Fertilisation then occurs, fusing the egg and sperm nuclei and creating the next sporophyte generation (9).
In the chain fern, the release of spores occurs from February to September in Italy and Corsica, and during the summer months in Algeria (1).