Even though there are four main parts to a flower, some flowers are incomplete. These incomplete flowers only contain three of the main parts instead of four. Depending on what parts a flower has, it can be male, female or androgynous since flowers are the reproductive organ of a plant. The four parts always occurs in concentric circles or whorls.
Sepals protect the flower before it opens, like a container for the flower. Sepals look much like leaves. Although they can come in any color, they usually come in green or brown. They are first part of the flower as you move up from the stem. Sepals are very easy to spot sitting beneath the petals of an opened rose. As a group, multiple sepals are called a calyx. The calyx is considered an accessory part of the flower because it isn't strictly needed for reproduction.
Petals are usually the easiest part of a flower to identify because they are colorful and showy. They, too, are an accessory part, though they play a big role in reproduction since petals attract the attention of pollinators. Flowers create petals in multiples of three or five and all the petals in a flower are called the perianth. The clayx and perianth are together called the corolla.
Besides their visual attractiveness to pollinators, petals produce scent and nectar. Some petals, like those of the pansy, are edible.
The androecium is the term for all the stamens of a flower. The androecium can be considered male since stamens are responsible for pollen and pollen contains sperm. The stamen has two parts: the filament and the anther. The filament holds up an anther, while the anther produces pollen. The filament holds the anther in the air to make it easier for pollinators to reach the pollen produced by the anther.
The gynoecium can be considered the female part of the flower's reproductive system. The gynoecium is the collective terms for the flower's carpels, which are usually merged into a single pistil. The carpal has three parts. At the top, there is the stigma, where pollinators deposit pollen. The stigma is supported by the style, through which the sperm travels down to reach the eggs, also known as ovules. At the bottom is the ovary with the ovules there for fertilization. Once fertilized, the eggs will turn into seeds and the ovary ripens to fruit.