Q.
Read the following matches regarding the placentation:
(i) Dianthus - Free central
(ii) Cannabis- Marginal
(iii) Sunflower -Basal
(iv) Cucurbita -Axile
Which of these are correct?
Solution:
Placentation is the pattern or arrangement of ovules within the ovary of the flower. There are different types of placentation in the plant. They are:
Basal placentation: When the placenta is at the base of the ovary with a single ovule attached, it is known as basal placentation, e.g., Sunflower, Marigold.
Parietal placentation: When the ovary is one-chambered but due to the formation of the false septum becomes two-chambered, it is known as parietal placentation, e.g., Mustard, Cucurbita pepo, Cannabis sativa and Argemone.
Axile placentation: When the placenta is axial and the ovules are attached to it in a multilocular ovary, it is known as axile placentation, e.g., China rose, Tomato, lemon and Orange.
Free central placentation: When the ovules are borne on the central axis and septa are absent, it is known as free central placentation, e.g., Dianthus and Primrose.
Marginal placentation: When 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 known as marginal placentation, e.g., Pea.
Basal placentation: When the placenta is at the base of the ovary with a single ovule attached, it is known as basal placentation, e.g., Sunflower, Marigold.
Parietal placentation: When the ovary is one-chambered but due to the formation of the false septum becomes two-chambered, it is known as parietal placentation, e.g., Mustard, Cucurbita pepo, Cannabis sativa and Argemone.
Axile placentation: When the placenta is axial and the ovules are attached to it in a multilocular ovary, it is known as axile placentation, e.g., China rose, Tomato, lemon and Orange.
Free central placentation: When the ovules are borne on the central axis and septa are absent, it is known as free central placentation, e.g., Dianthus and Primrose.
Marginal placentation: When 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 known as marginal placentation, e.g., Pea.
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