Dianthus and Primrose have which placentation?

• A. Marginal placentation
• B. Free Central placentation
• C. Axile placentation
• D. Parietal placentation

Answer: (B)

Placentation describes how ovules are attached inside the ovary. In free central placentation, ovules are borne on a central column that runs through the center of the ovary and is not attached to the ovary walls. This central placenta is free from the walls, so you see ovules arranged along a central axis rather than along a margin or on inner walls. Dianthus (carnations) and Primrose commonly show this pattern, which is why this placentation type fits them.

To contrast briefly, marginal placentation has ovules along the fused margin of a simple pistil; axile placentation has ovules on a central axis within a multilocular ovary where the locules meet at the center; and parietal placentation has ovules on the inner walls of a multilocular ovary. The central, central-column arrangement in these two genera is the hallmark of free central placentation.