The gymnosperms are plants in which the ovules are not enclosed by any ovary wall and remain exposed, before and after fertilisation. Unlike bryophytes and pteridophytes, in gymnosperms, male and female gametophytes do not have independent free living existence rather they are fully dependent on sporophyte (main plant body differentiated into root, stem and leaves). Gymnosperms are heterosporous, i.e., they produce haploid
microspores and megaspores. The microspore develops into male gametophyte, called pollen grain, development of pollen grains takes place in microsporangia present on microsporophyll.