In $Pteridophytes$ / $Dryopteris$,meiosis occurs at the time of:

Multiflagellate male gametes (sperms) are found in

Statement $X :$ $Selaginella$ is a heterosporous,gymnosperm plant.
Statement $Y :$ It produces two different types of spores.

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

In which plants are heterosporous conditions found,and what structures do they produce?

The name "Walking Fern" is given because of: