What is the number of cells or nuclei present in the male gametophyte of Capsella?

Anther is generally composed of

In $Capsella$,meiosis takes place during

The figure below shows a three-dimensional view of an anther. Identify $P$ and $Q$.
$\quad\quad\quad\quad \quad P \quad\quad\quad\quad Q$

In flowering plants,the archesporium gives rise to.......

When mature anthers of $Datura$ $innoxia$ are cultured in a culture medium supplemented with phytohormones named kinetin,coconut milk,and plum juice,several embryos can be obtained floating inside the microsporangia. These embryos can develop into plants that are: