The flowering part of a plant or tree that will form the seeds or fruit is called a blossom and synonyms include bloom and flower. The noun can also refer to the state of such flowering. You shouldn't miss cherry blossom time in Washington, D.C.
As a verb, blossom means to produce flowers. Your favorite time of year may spring be when all the trees blossom and the air is perfumed with their scent. The verb blossom also means to begin to flourish and develop. If you are a teenager, you might be waiting to blossom and feel confident in your personality and grow into your gangly limbs.