Artificial flowers date back to ancient times. According to Absolute Astronomy, the early Chinese, Romans and Egyptians all use artificial flowers, as did several South American cultures.
Artificial plants can be made from many different materials. Polyester, silk and plastic are commonly used in production for retail, while homemade flowers are often constructed from soap, clay, paper or nylon stockings.
According to MidtownFlorist.com, silk artificial plants are usually the most realistic, but are also generally more expensive. Polyester is the material most commonly used, and provides an acceptable level of realism. Plastic flowers and leaves are obviously fake.