Question

With the help of diagrams, name and describe the different types of placentation seen in angiosperms.

Answer 1

1. Marginal placentation: In this type, the gynoecium is monocarpellary, the ovary is unilocular and placentas are borne on the fused margins of the same carpel. The ovules are borne along the ventral suture of the carpel. This condition is found in legumes.
2. Axile placentation: In this type of placentation, the gynoecium is multicarpellary and syncarpous, and the ovary is multilocular. The placenta is borne on the fused margins of the same carpel. The ovules are borne on confluent margins that meet on the central axis. This type of placentation is found in tomato, citrus, china rose, etc.
3. Parietal placentation: In this type, the gynoecium is  multicarpellary, syncarpous and the ovary is unilocular. The placenta is borne on the fused margins of the same carpel. This type of placentation occurs in watermelon and other cucurbits.
4. Free-central placentation: In this type, the gynoecium is multicarpellary and syncarpous, and the ovary is unilocular. The ovules appear to arise from the central column. This type of placentation is found in Dianthus Primula, etc.
5. Basal placentation: In this type, the ovary is unilocular and the solitary ovule appears to arise from the base of the ovary, as in sunflower.
6. Superficial placentation: In this type of placentation, the gynoecium is multicarpellary and syncarpous and most of the internal surface of the ovary wall is covered with ovules, as in water lily.