What is a fernery?

In the prothallus of a vascular cryptogam,the antherozoids and the egg mature at different times. As a result,.......

The stele of $Pteridium$ root is

$A$: Events precursor to the seed habit are seen in some members of pteridophytes.
$R$: Development of the zygotes into young embryos takes place within the female gametophyte.

If the number of chromosomes in the foot of a fern embryo is $8$,what should be the number of chromosomes in its spores?

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