Identify labelled part $'X'$ from the figure :
Microspore
Middle layer
Endothecium
Tapetum
Microsporangia develops in to
$A$ : Formation of mature male gametophyte requires one meiotic and one mitotic division in $60\;\% $ of the
angiosperms.
$R$ : Pollination occurs in three celled condition in majority of angiosperms.
Assertion : Pollen mother cells $(PMCs)$ are the first male gametophytic cells.
Reason : Each $PMC$ gives rise to two pollens.
The pollen grain represents
Endothecium and tapetum in anther are derived from