The arrangements of ovules within the ovary is known as placentation. What does the term placenta refer to ? Name and draw various types of placentations in the flower as seen in $T.S$. or $V.S$.
$\rightarrow$ Placenta : Placenta is a flat cushion like tissue, one or more ovules are attached on it. Various types of placentation seen in flower is shown below.
$\rightarrow$ Ovary bears one or more ovules attached to a flattened cushion like placenta.
$\rightarrow$ The arrangement of ovules within the ovary is called placentation.
$\rightarrow$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, e.g., 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.
Placentation in tomato and lemon is
Given below are two statements: One is labelled as Assertion $A$ and the other is labelled as Reason $R$:
Assertion $A$: A flower is defined as modified shoot wherein the shoot apical meristem changes to floral meristem.
Reason $R$: Internode of the shoot gets condensed to produce different floral appendages laterally at successive node instead of leaves.
In the light of the above statements, choose the correct answer from the options given below :
Carpels are fused in the flowers of
Tetradynamous condition is related to