On the basis of the number of stamens and their union,classify the types of stamens and provide examples.

(A-D) $\rightarrow$ The androecium is composed of stamens,which are the male reproductive organs of a flower.
$\rightarrow$ Each stamen consists of a filament and an anther.
$\rightarrow$ Based on the union of stamens,they are classified as follows:
$\rightarrow$ $1$. Polyandrous: When the stamens in a flower remain free,it is called polyandrous.
$\rightarrow$ $2$. Monoadelphous: When stamens are united into one bunch or bundle,it is called monoadelphous,e.g.,China rose.
$\rightarrow$ $3$. Diadelphous: When stamens are united into two bundles,it is called diadelphous,e.g.,pea.
$\rightarrow$ $4$. Polydelphous: When stamens are united into more than two bundles,it is called polydelphous,e.g.,citrus.
$\rightarrow$ Additionally,based on attachment: Epipetalous (attached to petals,e.g.,brinjal) and Epiphyllous (attached to perianth,e.g.,lily).