Calyx is the first or the outermost whorl of a flower consisting of units called sepals. Calyx helps in photosynthesis
because of having green color pigment called chlorophyll and it also protects flower in its bud stage.
Corolla is the second whorl of a flower consisting of units called petals. Petals are typically brightly colored or white. They attract animals that help in the pollination
and they also protect the reproductive organs of a flower.
Androecium is the third whorl of a flower consisting of units called stamens. Stamen is the male reproductive
part of a flower. It has two parts, the long and narrow stalk is called filament and the topmost part which is connected with filament is called anther. While filament support anther and anther produce yellowish powders called pollen
grains, which contains male sex cell or male gametes.
The gynoecium is the fourth or the innermost whorl of a flower. It bears the female reproductive organ called carpel. Each carpel consists of three parts stigma, style and ovary. The stigma is the sticky knob at the outer end of the stalk. The style is the portion of the stalk connecting the stigma to the ovary. The ovary is the round base that contains one or more undeveloped seeds called ovules.
Words to know
Angiosperm: Plant that produces flowers and seeds.
Photosynthesis : The process of making food by plants in the presences of sunlight, water and carbondioxide is called photosynthesis.
Pollination : The process of transferring pollen grains from the male anther of a flower to the female stigma of a flower is called pollination.
Pollen : Powdery grains that contain the male reproductive cells of angiosperms.
Sources and Citations
A flower is the reproductive part of a plant. It is the most attractive part of a plant. A flower has basically four whorls (rings) - (i) calyx, (ii) corolla, (iii) androecium and (iv) gynoecium. Flower having all four whorls is called complete flower and the flower having absences of any one of them is called incomplete flower. Flower having both sex organs androecium and gynoecium is called bisexual flower where as flower having only androecium or gynoecium is called unisexual flower.