Describe the various types of placentations found in flowering plants.

The types of placentation are: Marginal, where ovules are arranged along the margin of the ovary, as in pea; Axile, where ovules are placed on a central axis, as in tomato; Parietal, where ovules develop on the inner wall of the ovary, as in mustard; Free central, where ovules are borne on a central column not connected by septa, as in Dianthus; Basal, where a single ovule is attached at the base of the ovary, as in sunflower.