Development of embryo in $Selaginella$ is

In $Selaginella$,reduction division occurs during the formation of

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 one of the following species of $Selaginella$,the apex continues its vegetative growth beyond the formation of $strobilus$?

$Pteris$ and $Adiantum$ resemble each other in having:

$A$ mature ligule,having a prominent basal portion,is called