Question

Flowers are epigynous in
A. Allium
B. Helianthus
C. Oryza
D. Datura

Answer 1

Hint: Flowers are divided based on the position of the corolla, calyx, and androecium with relation to that of the ovary on the thalamus, into hypogynous, perigynous, and epigynous. The gynoecium is defined as the female reproductive organ of a flower and is composed of one or more carpels.

Complete Answer:
A carpel is composed of three parts namely stigma, style, and ovary. Flowers are divided into three types according to the site of calyx, corolla, and androecium to that of the ovary on the thalamus.

Let's see the classification in detail:
1. Hypogynous flowers: The flowers in which gynoecium is present at the highest position while the other parts are situated below it is called hypogynous flowers. The ovary in this variety is termed to be superior, e.g., mustard, china rose, Datura and alium.
2. Perigynous flowers: The flowers in which gynoecium is present at the centre and other parts of the flower are situated on the rim of the thalamus almost at the same level, they are called perigynous flowers. The ovary in the perigynous type of flowers is termed as inferior or half inferior, e.g., plum rose, peach, Oryza.
3. Epigynous flowers: In these flowers, the margin of thalamus is present upward enclosing the ovary completely and getting fused with it, the other parts of flower are present above the ovary. An epigynous flower's ovary is termed to be inferior as in flowers of guava and cucumber, and the ray florets of sunflowers and Helianthus.

So, our required option is B that is Helianthus.

Note: A typical flower is composed of four different types of whorls arranged successively on the swollen end of the stalk or pedicel, called thalamus or receptacle. The calyx is defined as the outermost whorl of a flower and the members are called sepals. Corolla is made up of petals.