Poppies, dandelions, mushrooms, cactus, and the dead bush when placed in a flower pot can be replaced with any other flower and will be 'eaten up'. But it will not replace the flower if it is any other type of foliage like any of the new flowers (excluding poppy), ferns, or saplings. The flowers affected with being replaceable can also be eaten up in Survival mode.
Duplicate of MC-31388 - If you have not, please use the search function in the future, to see if your bug has already been submitted. If you could not find the original report, please comment with the keywords you searched for.