Section I. Floral Structure and Function

No matter what shape, size, or color a flower may have, its basic parts are similar. Note the four sets of parts in the illustration below.

Side view of a flower showing four whorls of appendages

Each set of parts is considered to be a whorl, meaning it consists of three or more similar parts originating from a common node. Consider the series of metal rods holding out the fabric of an open umbrella. The rods all seem to arise from the same site at a point on the umbrella handle. Similarly, the typical flower shown here has sets of appendages extending in whorls from common nodes or positions on the flower.

If we imagine ourselves holding up a flower (rather than an umbrella) by its "handle" (the pedicel), we can see the whorls from the bottom up. Note that the region from which the first set of appendages arises is slightly enlarged. This is called the receptacle. In this example, all the parts described below arise from the receptacle of the flower.

Let's examine some of the main flower parts more closely.

After you've covered these, Test Your Understanding of Flower Structure and Function