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Question
What is a flower? Describe the parts of a typical angiospermic flower.
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Solution
A flower is a shoot which is specialized in taking part in the sexual reproduction of angiosperms.
Parts of Angiospermic Flower: A flower has a stalk called pedicel. The base of the flower is thick. It accommodates all the components. It is called thalamus. It has nodes and internodes. The various parts of the flower are called floral organs. They are of four types, namely Sepals, petals, stamens and carpels.
Sepal or Calyx: They are green outermost and lowermost floral organs. They can be free (polysepalous) or fused(gamosepalous). An extra whorl of green bracts called epicalyx may occur in some flowers. Sepals aids in protection and support other floral organs.
Petals or Corolla: They are brightly coloured flat leaf-like floral organs which lie inside to sepals and outside the stamens. They may be free (polypetalous) or fused (gamopetalous). Their major function is to attract pollinating animals.
Stamens or Androecium: They are male reproductive organs of a flower. They may be borne directly over the thalamus or attached to petals (epipetalous). Stamens can be free or fused by their filaments (adelphous condition), anthers (syngenesious) or both (synandrous). Each stamen has a thread like a stalk and knob-like anther. Anther is bilobed and has four sporangia. Pollen grains are formed inside the sporangia of the anther.
Carpels or Gynaecium: They are female reproductive organs of a flower. Carpels may be free (apocarpous) or fused (syncarpous). A free unit is called pistil. It has three parts, namely stigma, style and ovary. Stigma is the terminal part of the pistil which receives and nourishes the pollen grains. A style is a stalk that raises the stigma above the ovary. An ovary is a basal swollen part which bears ovules over the placentae. Ovules later ripen to form seeds while ovary develops into a fruit.
Parts of Angiospermic Flower: A flower has a stalk called pedicel. The base of the flower is thick. It accommodates all the components. It is called thalamus. It has nodes and internodes. The various parts of the flower are called floral organs. They are of four types, namely Sepals, petals, stamens and carpels.
Sepal or Calyx: They are green outermost and lowermost floral organs. They can be free (polysepalous) or fused(gamosepalous). An extra whorl of green bracts called epicalyx may occur in some flowers. Sepals aids in protection and support other floral organs.
Petals or Corolla: They are brightly coloured flat leaf-like floral organs which lie inside to sepals and outside the stamens. They may be free (polypetalous) or fused (gamopetalous). Their major function is to attract pollinating animals.
Stamens or Androecium: They are male reproductive organs of a flower. They may be borne directly over the thalamus or attached to petals (epipetalous). Stamens can be free or fused by their filaments (adelphous condition), anthers (syngenesious) or both (synandrous). Each stamen has a thread like a stalk and knob-like anther. Anther is bilobed and has four sporangia. Pollen grains are formed inside the sporangia of the anther.
Carpels or Gynaecium: They are female reproductive organs of a flower. Carpels may be free (apocarpous) or fused (syncarpous). A free unit is called pistil. It has three parts, namely stigma, style and ovary. Stigma is the terminal part of the pistil which receives and nourishes the pollen grains. A style is a stalk that raises the stigma above the ovary. An ovary is a basal swollen part which bears ovules over the placentae. Ovules later ripen to form seeds while ovary develops into a fruit.
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