Germination of spore and formation of gametophytic plant:
(i) The spore germinates in favourable conditions.
(ii) At the beginning of germination the exine of spore bursts out and the intine expands.
(iii) Then it turns into a 3 to 6 celled structure through repeatedly mitosis cell division
(iv) This 3-6 celled structure eventually turns into a heart shaped gametophytic plant, called fern prothallus through repeatedly mitosis cell division.
Characteristics of fern prothallus:
(i) It’s green in color.
(ii) It’s heart shaped.
(iii) The margin of it is one layered.
(iv) There is a grove at the widened part.
(v) At the posterior end, there are rhizoids which fix up the gametophytic plant with the soil and absorb water.
(vi) There are two reproductive organs in the prothallus which are:
- Archegonium and
- Antheridiurn
Characteristics of Archegonium:
i) It is situated at the lower end of the grove
ii) They are flask shaped and each archegoniurn comprises of water and neck.
iii) Only one ovum (n) is produced from each archegonium
Characteristics of Antheridium:
i) They are situated among the rhizoids at the lower end of the prothallus.
ii) Antheridium is oval shaped
iii) It produces numerous multi flagellated sperms.
