AN OVARY FROM FUSED LEAVES. “The female reproductive organ of flowering plants (angiosperms) is called the gynoecium and develops in the middle of the flower as congenitally fused carpels, which have evolved from leaves. After fertilisation, the gynoecium develops into a fruit that nurtures and protects the seeds inside until their dispersal at maturity.“
http://www.sciencedirect.com/science/article/pii/S0959437X16301903