Question : What is placentation ? Describe types of placentation .

1.	Question : What is placentation ? Describe types of placentation .
Answer» Solution :Ovary bears one or more ovules attached to a flattened cushion like placenta. The arrangement of ovules within the ovary is called placentation. The TYPES of placentation are as follow : (i) Marginal Placentation : In marginal placentation the placenta forms a ridge along the ventral suture of the ovary and the ovules are borne on this ridge forming two rows e.g. pea, bean. (ii) Axile Placentation : When the placenta is axial and the ovules are attached to it in a multilocular ovary, the placentaion is said to be axile. e.g. CHINA rose, tomato and lemon. (III) Parietal Placentation : In parietal 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, ee MUSTARD and Argemone. (iv) Free Central Placentation : When the ovules are borne on central axis and septa are absent ovary is one-chambered so it is called free central e.g. Dianthus and Primrose. (v) Basal Placentation : In basal placentation, the placenta develops at the base of ovary and a single ovule is attached to it, e.g. Sunflower,Wheat. Types of placentation : (a) Marginal (b) Axile (C) Parietal (d) Free central (e) Basal

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