Question

Flowers are unisexual in
A. Pea
B. Cucumber
C. China rose
D. Onion

Answer 1

Flower is the modified shoot and it is the reproductive unit in the angiosperms. Flowers consist of four whorls which are arranged on the thalamus. These four whorls are calyx, corolla, androecium and gynoecium.

Complete answer:
Flowers are unisexual in cucumber.
Types of flowers:

Bisexual flower: When a flower has both androecium (male reproductive organ) and gynoecium (Female reproductive organ), e.g., pea and hibiscus (China rose).
Unisexual flower: A flower having either only androecium (stamen) or carpel (gynoecium), e.g., maize.
Trimerous flower: When all the floral appendages (whorls) are in the multiple of three, e.g., daffodils and orchids.
Tetramerous flower: In this flower, floral whorls are in the multiple of four, e.g., members of Brassicaceae.
Pentamerous flower: In this flower, floral appendages are in the multiple of five, e.g., sunflower and rose.
Bracteate flower: Flowers with bracts (reduced leaf found at the base of the pedicel), e.g., China rose and tulip.
Ebracteate flower: Flowers without bracts, e.g., mustard.
The calyx (sepals) and corolla (petals) are non-essential and accessory organs. Androecium (stamen) and gynoecium (carpel) are the reproductive organs of a flower.
Calyx is the outermost whorl of the flower. The sepals are green in colour and protect the flower in the bud stage. Corolla is the second whorl of the flower and petals are generally bright coloured which makes the flower more attractive.
Androecium is the third whorl of the flower and it is the male reproductive system which is composed of stamens. Stamens consist of a filament and anther. Gynoecium is the fourth and last whorl of the flower and it is the female reproductive system composed of carpels. Carpels consist of ovary, style and stigma.

So the correct answer is option B.

Note: A sterile anther which does not produce pollen grains called staminode. In some flowers like lily, the calyx and corolla are not separate or distinct and this condition is known as perianth.