In the conventional simplified longitudinal representation of a flower, which…
2019
In the conventional simplified longitudinal representation of a flower, which option gives the top-to-bottom sequence of the stigma, style, ovary and thalamus?
- A.
Ovary, Stigma, Style and Thalamus
- B.
Style, Stigma, Ovary and Thalamus
- C.
Ovary, Style, Thalamus and Stigma
- D.
Stigma, Style, Ovary and Thalamus
Attempted by 3 students.
Show answer & explanation
Correct answer: D
Concept
The pistil (gynoecium) has a stigma at the top of the style and an ovary at its base. The thalamus (receptacle) is a separate floral axis, and its position relative to the ovary varies among flower types.
Application
The options use the conventional simplified arrangement in which the thalamus supports the ovary from below. Read the structures downward:
Pollen is received on the stigma at the upper end.
The style forms the stalk below the stigma.
The ovary is the enlarged basal part of the pistil.
In this representation, the thalamus is the supporting floral base below the ovary.
Contrast
‘Ovary, Stigma, Style and Thalamus’ begins with a basal pistil part and then moves upward before moving down again.
‘Style, Stigma, Ovary and Thalamus’ swaps the relative positions of the style and stigma.
‘Ovary, Style, Thalamus and Stigma’ places the floral base between pistil parts and ends with the uppermost structure.
Cross-check and result
The pistil itself gives the invariant order stigma → style → ovary. Under the simplified arrangement specified in the stem, the supporting thalamus follows beneath the ovary, so the required sequence is Stigma, Style, Ovary and Thalamus.