Duble Flower Bug

When breaking the bottom of any of the 2 block high flowers(exept poppy)
the top of a poppy came upp(ore watherev the name of it is)
what i thaugt would happend was that it would just break.

step one
find any 2 block high flowers

step two
brak the bottom of this flower and the top of a poppy shuld apper for