The essential parts of a flower can be considered in two parts: the vegetative part, consisting of petals and associated structures in the perianth, and the reproductive or sexual parts. A stereotypical flower consists of four kinds of structures attached to the tip of a short stalk.  Each of these kinds of parts is arranged in a whorl on the receptacle.  The four main whorls (starting from the base of the flower or lowest node and working upwards) are as follows: