$\displaystyle \small \bullet$ Reproduction is a process of producing offspring, and is aimed to preserve individual species.
$\displaystyle \small \bullet$ In higher plants reproduction may be asexual or sexual.
$\displaystyle \small \bullet$ In sexual reproduction, fusion of male and female gametes takes place.
$\displaystyle \small \bullet$ In asexual reproduction, sex organs are not involved and reproduction takes place by means of vegetative methods.
$\displaystyle \small \bullet$ Modes of Reproduction in Flowering plants or Angiosperms
i) Asexual or vegetative reproduction: The offsprings are produced from somatic cells.
ii) Sexual reproduction: The offsprings are produced by fusion of male and female gametes.
Structure of Flower
$\displaystyle \small \bullet$ The flower is a highly specialized reproductive shoot.
$\displaystyle \small \bullet$ Each typical flower consists of four distinct types of members arranged in four separate but closely set whorls one above the other.
$\displaystyle \small \bullet$ The lower two whorls are called accessory whorls and upper two are called essential or reproductive whorls.
$\displaystyle \small \bullet$ Reproductive whorls consists of two kinds of sporophylls:
(i) microsporophylls/stamens
(ii) megasporophylls/carpels
Parts of Flower
$\displaystyle \small \bullet$ Pedicel: It is the stalk of the flower, which may be short, long or even absent.
$\displaystyle \small \bullet$ Receptacle/Thalamus: It is the swollen or expanded portion of the stalk which bears the floral leaves.
$\displaystyle \small \bullet$ Whorls:
(i) Calyx
$\displaystyle \small \circ$ It is the lowermost whorl.
$\displaystyle \small \circ$ It is a collection of sepals.
$\displaystyle \small \circ$ It is generally green and leaf-like.
$\displaystyle \small \circ$ It protects the flower bud before it opens.
(ii) Corolla
$\displaystyle \small \circ$ It is inner to sepals.
$\displaystyle \small \circ$ It is a collection of petals.
$\displaystyle \small \circ$ The petals are generally large, brightly colored and may have fragrance.
$\displaystyle \small \circ$ They help in pollination by attracting insects.
(iii) Androecium
$\displaystyle \small \circ$ It is the male whorl of the flower.
$\displaystyle \small \circ$ It is a collection of stamens/microsporophylls.
$\displaystyle \small \circ$ Each stamen is a modified leaf and has two parts
1. Filament: A long slender stalk that carries food and water to anther.
2. Anther: It is bi-lobed structure present at the tip of the filament. It generally bears four pollen sacs which are filled with pollen or pollen grains i.e. male gamete.
(iv) Gynoecium/Pistil
$\displaystyle \small \circ$ It is the female whorl of the flower.
$\displaystyle \small \circ$ It is a collection of carpels/megasporophylls.
$\displaystyle \small \circ$ Each carpel has three parts
1. Stigma: Topmost part that receives the pollen grain.
2. Style: Forms the neck of the carpel
3. Ovary: The swollen basal part of the carpel that contains one or more ovules.
Functions of a Flower
1) Development of pollen and egg: Flowers are modification of shoot to perform the function of sexual reproduction. Development of pollen grains and embryo sac.
2) Pollination: Flowers of most of the angiosperms are shaped variously to help diverse modes of pollination.
3) Fertilization: Flowers provide seat for germination of pollen, development of pollen tube, formation of gametes and fertilization.
4) Development of seeds and fruits: The ovary part of the carpel gets transformed into fruit and the ovules are transformed into seeds after fertilization.
5) Dispersal of seeds and fruits: Some floral parts like calyx and various modifications in ovaries help in the dispersal of fruits and seeds.
$\displaystyle \small \bullet$ In higher plants reproduction may be asexual or sexual.
$\displaystyle \small \bullet$ In sexual reproduction, fusion of male and female gametes takes place.
$\displaystyle \small \bullet$ In asexual reproduction, sex organs are not involved and reproduction takes place by means of vegetative methods.
$\displaystyle \small \bullet$ Modes of Reproduction in Flowering plants or Angiosperms
i) Asexual or vegetative reproduction: The offsprings are produced from somatic cells.
ii) Sexual reproduction: The offsprings are produced by fusion of male and female gametes.
The Flower
$\displaystyle \small \bullet$ The flower is a highly specialized reproductive shoot.
$\displaystyle \small \bullet$ Each typical flower consists of four distinct types of members arranged in four separate but closely set whorls one above the other.
$\displaystyle \small \bullet$ The lower two whorls are called accessory whorls and upper two are called essential or reproductive whorls.
$\displaystyle \small \bullet$ Reproductive whorls consists of two kinds of sporophylls:
(i) microsporophylls/stamens
(ii) megasporophylls/carpels
Parts of Flower
$\displaystyle \small \bullet$ Pedicel: It is the stalk of the flower, which may be short, long or even absent.
$\displaystyle \small \bullet$ Receptacle/Thalamus: It is the swollen or expanded portion of the stalk which bears the floral leaves.
$\displaystyle \small \bullet$ Whorls:
(i) Calyx
$\displaystyle \small \circ$ It is the lowermost whorl.
$\displaystyle \small \circ$ It is a collection of sepals.
$\displaystyle \small \circ$ It is generally green and leaf-like.
$\displaystyle \small \circ$ It protects the flower bud before it opens.
(ii) Corolla
$\displaystyle \small \circ$ It is inner to sepals.
$\displaystyle \small \circ$ It is a collection of petals.
$\displaystyle \small \circ$ The petals are generally large, brightly colored and may have fragrance.
$\displaystyle \small \circ$ They help in pollination by attracting insects.
(iii) Androecium
$\displaystyle \small \circ$ It is the male whorl of the flower.
$\displaystyle \small \circ$ It is a collection of stamens/microsporophylls.
$\displaystyle \small \circ$ Each stamen is a modified leaf and has two parts
1. Filament: A long slender stalk that carries food and water to anther.
2. Anther: It is bi-lobed structure present at the tip of the filament. It generally bears four pollen sacs which are filled with pollen or pollen grains i.e. male gamete.
(iv) Gynoecium/Pistil
$\displaystyle \small \circ$ It is the female whorl of the flower.
$\displaystyle \small \circ$ It is a collection of carpels/megasporophylls.
$\displaystyle \small \circ$ Each carpel has three parts
1. Stigma: Topmost part that receives the pollen grain.
2. Style: Forms the neck of the carpel
3. Ovary: The swollen basal part of the carpel that contains one or more ovules.
1) Development of pollen and egg: Flowers are modification of shoot to perform the function of sexual reproduction. Development of pollen grains and embryo sac.
2) Pollination: Flowers of most of the angiosperms are shaped variously to help diverse modes of pollination.
3) Fertilization: Flowers provide seat for germination of pollen, development of pollen tube, formation of gametes and fertilization.
4) Development of seeds and fruits: The ovary part of the carpel gets transformed into fruit and the ovules are transformed into seeds after fertilization.
5) Dispersal of seeds and fruits: Some floral parts like calyx and various modifications in ovaries help in the dispersal of fruits and seeds.
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