Question

Thalamus is
A)Base of flower
B)Base of ovary
C)Modification of pollen
D)Modification of petal

Answer 1

Flower is defined as a reproductive part of a plant. Flower consists of floral whorls calyx, corolla, androecium and gynoecium arranged around the thalamus. Calyx and corolla are termed as the accessory parts. Androecium, gynoecium is termed as the reproductive essential parts of a flower.

Complete answer:
Thalamus is basically the receptacle that is located in angiosperms at the base of flowers and it is the thickened part of the stem from which the various flowers grow. There are three types of flowers on the premises of relation to position in various types of floral organs

a) Hypogynous
The upper part of the thalamus is slightly swollen and aligned to form a cushion like a disc. The gynoecium is located at the top of the thalamus. All parts calyx, corolla, androecium are present below the level of ovary and as these are separated from ovary, so that ovary can be observed from outside. This type of ovary is termed as the superior ovary. Examples include: Brassica, citrus, mustard, China rose, brinjal.

b) Perigynous
In perigynous kinds of flowers the thalamus may be - disc shaped cup-shaped and flask-shaped. In disc shaped thalamus, the ovary of gynoecium is located in the centre and all other floral whorls lie on the peripheral side. Example: Pea
In cup-shaped thalamus, the ovary develops from the bottom of the cup and floral whorls arise at the rim of the cup. E.g. Prunus.
In flask-shaped thalamus, the ovary is located at the bottom of flask and floral whorls are connected at the mouth of flask. E.g. Rose, plum and peach.

Hence, the correct answer is option (A)

Note: Thalamus is defined as a kind of modified stem and is present near the stalk of the flower. Near the stalk they divide to form nodes and internodes. Thalamus is used to supply nutrients. It acts as a base of the flower.