The pteridophytes reproduce both by the Vegetative and Sexual methods.
Vegetative reproduction:
The vegetative reproduction is also a common type of reproduction in the pteridophytes. It helps to increase the number of population under unfavourable conditions also. It is also advantageous since it can produce large number of individuals which are genetically identical too. The vegetative reproduction occurs by fragmentation as in Selaginella rupestris, surface or underground tuber formation. The adventitious buds are produced from the axils of leaves as in Dryopteris. Fragmentations are the type of propagation present in the floating ferns Azolla and Salvinia.
Sexual reproduction:
The reproductive structures are borne on the terminal branches called strobilus or spike. The strobili possess ligule in its axils; the sporophylls are arranged in the form of clusters. Some sporangia possess large spores called as the megaspores and the sporangia so known as the mega sporangium which is borne on the megasporophyll. Some other sporangia bear microspore and so the sporangium is known as the microsporangium which is again borne on the megasporophyll. If two types of spores are present in a single plant species then it is known as the heterosporous pteridophytes. Most of the pteridophytes are homosporous; their gametophytes are exosporic. The heterosporous pteridophytes produce microspores and megaspores which germinate to give rise to male and female gametophytes respectively. The sporophyte represents the diploid phase and the gametophyte represents the haploid phase in the life cycle. The gametophyte is monoecious in the homosporous plants and dioecious in the heterosporous pteridophytes. The male gamete produces the antheridia and the female gametes produce the archegonia. The fusion between them results in the formation of the diploid zygote. This zygote gives rise to the sporophyte; sporophyte after meiosis gives rise to the haploid spore which forms the haploid gametophyte again there by completing the life cycle.
When the gametophyte directly give rise to sporophyte without syngamy. The phenomenon is known as the Apogamy. When the sporophyte give rise to gametophyte without formation of spores. The phenomenon is known as the Apospory.
