Placentation is the arrangement of the ovules in the ovary and their attachment to it. Placentation are of various type in the angiosperms - marginal, axile, central, parietal, basal, and free central. In marginal placentation, ovules are attached to the ridge formed on the ventral suture of the ovary. The Pea plant has this arrangement.

In parietal, the ovules are attached to the inner wall or towards the periphery of the ovary, observed in mustard plant and even argemone and poppy. Sunflower and marigold show basal placentation where the ovules are attached at the base of the ovary. Dianthus and primrose display free-central placentation and in it the ovules are attached at the central axis of the ovary without any septa present like in axile pattern.