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The arrangement of ovules within the ova...

The arrangement of ovules within the ovary is known as placentation. What does the term placenta refer to ? Draw various types of placentations in the flower as seen in T.S. and V.S.

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Placenta is a soft cushion like tissue. Ovules are attached to inner surface of ovary.
The arrangement of ovules within the ovary is known as placentation. The placentation are of different types namely marginal, axile, parietal basal, central and free central etc.
Marginal Placentation :
In this type of placentation the placenta forms a ridge along the ventral suture of the ovary and the ovules are borne on this ridge forming two rows as in pea.
Axile Placentation :
In this type of placentation, when the placenta is axial and the ovules are attached to it in a multilocular ovary, the placentation is said to be axile as in china-rose, tomato and lemon.
Parietal Placentation :
In this type of placentation, the ovules develop on the inner wall of the ovary or on peripheral part. Ovary is one chambered but it becomes two chambered due to the formation of the false septum, eg, mustard.
Free Central Placentation :
In this type of placentation, when the ovules are borne on central axis and septa are absent so ovary is one chambered. e.g. Dianthus and Primose ?
Basal Placentation :
In basal placentation, the placenta develops at the base of ovary and a single ovule is attached to it. eg. sunflower.
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