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Placentation Bot 222 Reem Alotaibi
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Placentation 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.
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Placentation The arrangement of ovules on the placenta inside the ovary is called placentation. There are several types of palcentation a. Marginal placentation: In this type, the ovary is monocarpellary, monolocular and the placenta is on the ventral suture. The ovules are attached to the placenta which is on the margin. e.g. Beans, Pea, etc
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Placentation b. Axile placentation :
In this type, the ovary has two or more carpels, syncarpous, and has two or more locules. The ovules are borne at or near the centre on the axis formed by the union and fusion of the septa (partitions) and usually in vertical rows. e.g., Apple, Hibiscus etc.
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Placentation c. Free Central placentation:
In this type the ovary is monolocular, wherein the ovules are borne on a central axis that reaches the top of the ovary. e.g., Primula, Sandal Wood. d. Free basal placentation: Similar to free central but the placental column does not reach the top of the ovary. e.g., Portulaca, Celosia.
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Placentation Pariental Placentation:
In this type, the ovary has two or more carpels, and is syncarpous, and monolocular. Here there are as many placentae as the number of carpels and the ovules are attached to those placentae at the periphery. e.g., Cucurbita, Argemone
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Placentation e. Basal Placentation:
In this type, the ovary is monolocular. The ovules are few or reduced to one and borne at the base of the ovary. The ovule when solitary often fills the ovary cavity. e.g., Sunflower. f. Apical placentation: The ovary is monolocular. The one or two ovules are borne at the roof of the ovary. e.g., Morus
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