Flowers have four main parts—all of which help to identify the flower and to allow the flower to be easily pollinated, often by specific pollinators. If a flower has all of these parts, it is called complete; if it lacks any of them, it is called incomplete. For example, some flowers may not have any petals or sepals. In terms of sexual reproduction in flowers, only stamens and pistils are necessary; some flowers contain only the male structures, while others only the female reproductive structures. Flowers with both structures are called perfect, but if they lack either one or the other they are called imperfect.

The following is a list of the plant parts and some of their components.