Thanks to ancient wall art we now know that the first known usage of flower arrangements took place in the time of the early Egyptians. The ancient culture revered the majestic nature of flowers and used them in a variety of ways. Most notably delicate arrangements of flowers were a staple in ceremonies such as funerals. The Egyptians are also known for putting cut flowers in vases, just like we do now.
The idea of utilizing flowers to mark special events and religious processions spread to other ancient peoples. The Greeks and Romans regularly created floral arrangements for their various religious and spiritual ceremonies. These arrangements were less likely to be contained inside a vase. However, beautiful wreath like arrangements came to exist thanks to the artful Romans.
Eventually this method drifted its way to Asia. The flowers utilized were often believed to have significant spiritual value, based on their species. The common theme of utilizing floristry to highlight spiritual events continued within this society. Staple elements such as bamboo were added to the mix.
In Europe the idea of using formed bouquets in religious places began about a millennia ago. In the beginning the hobby was pretty much restricted to monastery purposes. Though the first inklings were present at this time, it was another 500 years before the idea became common. This is when floristry really began to develop more into what it is now. Fruit mixed in with flowers was the contribution that this period of time brought to the world.
The art form developed simultaneously in the US as initial settlers brought it with them on their pilgrimage to the new world, and eventually the PA flower shop was born. The Philadelphia florist tradition is maintained by those who have been formally trained in post graduate education as well as those got their education through internship or self study. The arrangements that are marketed now are utilized for ceremonial and religious events such as weddings and funerals as well as gifts for all occasions. These days it's not unusual to see flowers at church as well as someone's dining room table just for a little beauty. Now you can purchase arrangements from a PA flower without ever even leaving the house.