Reproduction of Psilotum

                                       Reproduction

Vegetative reproduction:

Vegetative reproduction in Psilotum takes place by formation of gemmae, develop freely in large number on the rhizome. These gemmae are small, oval bodies, one cell in thickness. Gemmae germinate either before or after detachment from the sporophyte and form new plants.

 Asexual reproduction:

Plant bears large and conspicuous sporangia at the distal ends of the dichotomously branched shoots. In Psilotum the sporangia are borne in triads on the adaxial side of the appendage or leaf at the point of dichotomy and they are slightly raised on broad but short stalks. As the sporangia are fused with one another so the group is often referred to as synangium. Each mature sporangium or sporangial complex is 3 lobed and each lobe  contains a spore sac with numerous spores of one kind (homosporous). The sporangial wall is multi layered.  The mature sporangium dehisces by a vertical slit.

Structure of the gametophyte: Spore is the first cell of the gametophyte. Each spore is bilaterally symmetrical with outer delicate and thin reticulate wall. A spore germinates after about 4 months and develop into a gametophytic plant. The gametophytic plant body is small, brown in colour, sub terranean and saprophytic in nature, the mature gametophyte is irregularly or dichotomously branched, elongated and covered with brownish hair like rhizoids. Cells of the gametophyte filled with mycorrhizal fungus.

Sexual reproduction:

Gametophytes are homothallic ie. monoecious. Antheridia and archegonia develop in large number on throughout the gametophyte. .

Antheridia: Antheridia begin to develop on the gametophyte earlier than archegonia, each antheridium is a projected spherical body with a jacket of single layer of cells. Within the jacket of the antheridium, there is numerous spiral and multiflagellate sperms.

Archegonia: The archegonia are sunken with short projecting neck which breaks away at maturity. The neck of the archegonium is 4-5 cells in height and carries 2 neck canal cells. The venter contains 1 ventral canal cell and an egg.

Fertilization: As the archegonia mature there is continuous disintegration of neck canal cells and ventral canal cell which leaves a passageway for entrance of antherozoid into the venter of the archegonium. Finally, fertilization occur inside the venter.

After fertilization, the diploid zygote enlarges and starts to divide to form the young embryo, the embryo continues its growth with elongation of covering calyptra (gametophytic origin). Finally,  calyptra rupture and embryo grow to form the young sporophyte of Psilotum (at the same time gametophyte gradually degenerates).