An ovule is a structure that is part of the female reproductive organ in seed plants, and it is what eventually develops into a seed after fertilization. It is located inside the portion of the flower called the gynoecium, which is the female reproductive part of the flower. The ovule is contained in the ovary at the bottom of a vase-like structure called the carpel, which has a neck called a style and an opening at the top called a stigma. The ovule consists of three parts: the integument, which forms its outer layer, the nucellus, which is the remnant of the megasporangium, and the female gametophyte, which is found at the very center.

The ovule is an essential part of flower reproduction. When an ovule is fertilized, it produces seeds, which are dispersed and produce new plants. The ovary of the gynoecium produces one or more ovules and ultimately becomes the fruit wall. Different patterns of ovule attachment, or placentation, can be found among plant species. In gymnosperms, such as conifers, the ovules are found on the scales of female cones, while in angiosperms, which are flowering plants, the ovules are found inside of the ovary within the carpel.

In summary, an ovule is a structure that is part of the female reproductive organ in seed plants, located inside the gynoecium of the flower, and it is what eventually develops into a seed after fertilization.