In $Dryopteris$,the placenta is the site of attachment for:

$A$: In $Equisetum$,sexual reproduction occurs through sex organs like antheridia and archegonia.
$R$: In pteridophytes,the gametophytic stage is long-lived and responsible for sexual reproduction.

Some genera like $Selaginella$ and $Salvinia$ produce two kinds of spores. What are such plants called?

The heart-shaped form of prothallus represents:

In the case of heterosporous pteridophytes,the gametophyte is:

Brown hair found at the base of $Pteris$ leaves are: