The fourth series, the innermost one, consists of the carpels. The carpels are the female reproductive parts of the flower. There can be one to many single carpels or the carpels may be fused into one structure. Together the carpels form the gynoecium (which means "the female's house"). Each carpel is composed of an ovary, which contains the ovules, a stigma, which is the pollen receptive region, and a style, which connects the stigma to the ovary.

We do not use the word "pistil" in this class; this is discussed in a subsequent slide. This example is wild geranium (Geranium maculatum).