This is the female part of the flower and consists of three parts; stigma, style, and ovary
Flower is a highly specialized reproductive shoot. A typical flower has 4 whorls, one after the other on a stalk. The stalk can be short or long. The two lower whorls are not directly involved in reproduction. Therefore, they are called accessory whorls. Upper two whorls are directly involved in reproduction. Therefore, they are called reproductive whorls. The reproductive whorl is made up of microsporophylls and megasporophylls. Microsporophylls are called stamens and megasporophylls are called carpels in anthophytes/ angiosperms. Some flowers have both stamens and carpels in the same flower and some flowers possess either carpels or stamens. Third whorl is known as the androecium which is the male whorl. Fourth whorl is known as the gynoecium, which is the female part of the flower.
Carpels are the megasporophylls. Megasporophylls are modified leaves which bear ovules. Depending on the number of carpels present, the pistil can be either simple or compound. When the pistil carries only one carpel, it is said to be a simple pistil, and when the pistil carries two or more, the pistil is said to be a compound pistil. In the compound pistils, the carpels may remain free, or they may remain fused. Each carpel possesses three parts. Those are stigma, style and ovary. Stigma is at the upper end of the style, and it is the structure that receives the pollen grains. Structurally, the stigma is like a knob, and it is sticky in order to receive the pollen grains. Style is like an extension of the ovary, which is like a very thin and a narrow tube. It bears the stigma at the top. Surface of the style may be very smooth and hairy in order to trap pollen grains. At the bottom of the style is a swollen looking structure, which is the ovary. The ovary can be single chambered or multiple chambered. The ovary contains ovules. Each ovule has an embryo sac inside. After fertilization, the ovary gives rise to the fruit, and the ovules give rise to seeds.