Question

Why do androecium and gynoecium of same flower matures at different time?

Answer 1

it is nature's preparation OR because there might be many of each kind such that though if one did not mature some other will

Answer 2

the androecium and gynoecium of same flower mature at different times to avoid autogamy .
if the plant undergoes continuous self pollination then it suffers from inbreeding depression... which finally results in sterility of plant...

hope it helps !! ❤️✌️