NEET 2020 Botany Question 20 Solution
Question
Ray florets have:
- (1)Inferior ovary
- (2)Superior ovary
- (3)Hypogynous ovary
- (4)Half inferior ovary
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Ray florets have:
In ray florets of sunflower (Asteraceae), the thalamus encloses the ovary completely and fuses with it, with calyx, corolla, and stamens arising ABOVE the ovary (Epigynous flower). Therefore, ray florets have an Inferior Ovary! Mark Option (1) in 5 seconds.
Based on the spatial insertion of calyx, corolla, and androecium relative to the gynoecium on the thalamus: - 1. Hypogynous Flower (Superior Ovary): Gynoecium occupies the highest position on the convex/conical thalamus while other floral whorls arise below it (e.g. mustard, China rose, brinjal). - 2. Perigynous Flower (Half-Inferior Ovary): Gynoecium is situated in the centre of a cup-shaped thalamus, and other parts arise on the rim of the thalamus at the same level (e.g. plum, rose, peach). - 3. Epigynous Flower (Inferior Ovary): The margin of the hollowed cup-shaped thalamus grows completely upward, enclosing and fusing with the ovary wall. The sepals, petals, and stamens arise above the top of the ovary. The ovary is consequently inferior. - NCERT explicitly provides three canonical examples of epigynous flowers with inferior ovaries: guava, cucumber, and the ray florets of sunflower.
In the composite head (capitulum) of sunflower (*Helianthus annuus*), the marginal zygomorphic strap-shaped ray florets are pistillate or sterile and strictly epigynous, with the ovary situated inferior to the attached ligulate petal tube.
Diagnose every choice: Know exactly why the right option works and why distractors fail.
Correct. Ray florets of sunflower are epigynous and possess an inferior ovary.
Incorrect. Superior ovaries belong to hypogynous flowers (mustard, brinjal).
Incorrect. "Hypogynous ovary" is a misnomer; the flower is hypogynous and the ovary is superior.
Incorrect. Half-inferior ovaries characterize perigynous flowers (plum, rose, peach).
Both ray florets (marginal ligulate) and disc florets (central tubular) of the sunflower capitulum have an inferior ovary (epigynous). Do not confuse epigynous flowers (guava, cucumber, sunflower) with perigynous flowers (plum, rose, peach).
"In epigynous flowers like ray florets of sunflower, other floral parts arise above the ovary, making the ovary inferior."
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