Define placentation. Explain its types.

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1. Placentation: The mode of arrangement of ovules on the placenta within the ovary is called placentation.

2. Types of placentation: 

a. Marginal: Ovules are placed on the fused margins of unilocular ovary, e.g. Pea, Bean etc. 

b. Axile: Ovules are placed on the central axis of a multilocular ovary, e.g. China rose, Cotton, etc. 

c. Parietal: Ovules are placed on the inner wall of unilocular ovary of multicarpellary syncarpus ovary, e. g. Papaya, Cucumber, etc. 

d. Basal: Single ovule is present at the base of unilocular ovary, e.g. Sunflower, Rice, Wheat. 

e. Free central: Ovules are borne on central axis which is not attached to ovary wall, e.g.Argemone, Dianthus.

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