Question

Question 15 Describe the arrangement of floral members in relation to their insertion on thalamus?

Class XI Biology Chapter - Morphology of Flowering Plants Page 83

Answer 1

Based on the position of calyx, corolla and the androecium in respect of ovary on the thalamus, flowers may be of three kinds :
(a) Hypogynous flower: Gynoecium located at highest position and rest whorls of flower lies below it e.g., Mustard.
(b) Perigynous flower : The gynoecium is situated in centre and other parts of flower lie on the rim of thalamus almost at same level. Ovary is half inferior e.g., Rose.
(c) Epigynous flower: The margins of thalamus grows
upwards enclosing the ovary fully and getting united to it, the rest parts of the flower arise above the ovary e.g., Guava.

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Answer 2

Based on the position of the calyx, corolla, and androecium (with respect to the ovary on the thalamus), the flowers are described as hypogynous, perigynous, and epigynous.

1] Hypogynous flower : In hypogynous flowers, the ovary occupies the highest position on the thalamus while other floral parts are situated below it. In such flowers, the ovary is superior e.g., China rose, mustard etc.

2] Perigynous flower : In perigynous flowers, the ovary is situated at the centre and other floral parts are arranged on the rim of the thalamus. The ovary here is said to be half inferior e.g., plum, rose, peach.

3] Epigynous flower : In epigynous flowers, the thalamus grows around the ovary fusing with its wall. The other floral parts are present above the ovary. Hence, the ovary is said to be inferior e.g., flowers of guava and cucumber.