From the evolution point of view, retention of the female gametophyte with developing young embryo on the parent sporophyte for some time, is first observed in:

Step-by-step solution

The megaspores and microspores germinate and give rise to female and male gametophytes, respectively. (i) The female; gametophytes in these plants are retained on the parent sporophytes for variable periods. (ii) The development of the zygotes into young embryos takes place within the female gametophytes. (iii) This event is a precursor to the seed habit considered an important step in evolution.