Question
Thu July 19, 2012 By: Sivendu Sivendu
 

explain different types of placentation in detail

Expert Reply
Fri July 20, 2012
The arrangement of ovules within the ovary is known as placentation. The different types of placentation found in plants are:
  • Basal placentation: The placenta is at the base (bottom) of the ovary and a single ovule is attached to it. Example: Sunflower, marigold.
  • Parietal placentation: Here ovary is one-chambered but it becomes two- chambered due to the formation of the false septum. The ovules develop on the inner wall of the ovary or on peripheral part. E.g. - mustard and Argemone.
  • Axile placentation: The placenta is axial and the ovules are attached to it in a multilocular ovary. Example: China rose, tomato and orange.
  • Free central placentation: The ovules are borne on central axis and septa are absent. Example - Dianthus and Primrose
  • Marginal placentation: Here the placenta forms a ridge along the ventral suture of the ovary and the ovules are borne on this ridge forming two rows. It is characteristic of legumes like pea.
Home Work Help