Bot 222 Reem Alotaibi. Placentation The arrangement of ovules within the ovary is known as...
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Transcript of Bot 222 Reem Alotaibi. Placentation The arrangement of ovules within the ovary is known as...
PlacentationBot 222
Reem Alotaibi
PlacentationThe 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.
Placentation
Placentation
Placentation
PlacentationThe 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
Placentationb. 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.
Placentationc. 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.
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
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
Placentation
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