reproduction in flowering plant one shot
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Floriculture – Science of cultivation, breeding and marketing of flowers.
l Most of the important angiospermic characters are found in Capsella (Shepherd's purse) and it is easily
available so that it is considered as a "Typical Angiosperm".
l It is an annual plant and grows as a weed during the winter season in the field.
l The main plant body of the Capsella is a sporophyte (diploid) and it is differentiated into root, stem and
leaves.
l Capsella is a heterosporous plant, it means two different types of spores are formed in the life cycle which
are classified into two categories in which male spores are called microspores and female spores are
called megaspores.
l Flowers are object of aesthetic, ornamental, social, religious and cultural values.
l Flower is a fascinating organ of angiosperms.
l Flowers are seat of sexual reproduction in angiosperms.
l To a biologist, flowers are morphological and embryological marvels and site of sexual reproduction.
FLOWER IS A MODIFIED SHOOT
l According to Goethe, Flower is a modified shoot. Flower has a stalk called pedicel. Free end of the pedicel
is flattened or dome shaped which is called thalamus. The thalamus is a type of modified stem, on which
nodes and internodes are present.
Nodes are present very close to each other because internodes are small, highly reduced in the thalamus.
l The whorls present in the flower are the modifications of leaves and these are arranged in four circles on the
thalamus.
l The four nodes are present on the thalamus, in which first modified leaves (calyx) are attached on the first
lowermost node.
l The corolla born on the second node, androecium is present on the third node and gynoecium on the
fourth node in uppermost position.
l In some of the plants the length of internode increases, between the calyx and corolla and is called anthophore
e.g. Silene plant, Dianthus.
l If the length of internode between the corolla and androecium increases then it is called androphore e.g.
Passiflora.
l If the internode between the androecium and gynoecium increases, then it is called gynophore. e.g. Capparis.
If both androphore and gynophore are present in the same flower, then it is called gynandrophore or
androgynophore. e.g. Gynandropsis pentaphylla or Cleome gynandra.
l Sepals are also modified vegetative leaves. In Mussaenda flower, one sepal of calyx is modified into leaf like
bright and attractive yellow coloured structure which is called "Advertising flag". It helps in pollination
l On the basis of above examples, we can prove that "Flower is a modified shoot".
MONOCARPIC PLANTS
l The plants in which flowering and fruiting takes place only once in the whole life span are called monocarpic
e.g. Annual & Biennial plants.
l Plants the annual and biennial types, show clearcut vegetative/juvenile, reproductive and senescent
phases, but in the perennial species it is vey difficult to clearly define these phases.
POLYCARPIC PLANTS :
l The plants in which flowering and fruiting takes place many times in their entire life span are known as
polycarpic e.g. Perennial plants.
EXCEPTIONS :
l Bamboo, century plant (Agave americana) Strobilanthus kunthiana are perennial plants but they are the
examples of monocarpic plants.
l Bamboo species flower only once in their life time, generally after 50-100 years, produce large
number of fruits and die.
l Strobilanthus kunthiana (Neelakuranji) flowers once in 12 years. It flowered during
sep.-oct. 2006. Its mass flowering transformed large tracks of hilly areas in Kerala, Karnataka
and Tamilnadu into blue stretches and attracted a large number of tourists.
l Sexual reproduction involves the formation and fusion of gametes. It is a complex and slower process as
compared to asexual reproduction.
l Events of sexual reproduction may be categarised into pre-fetilisation, fertilisation and post - fertilisation events.
PRE-FERTILIZATION STRUCTURES AND EVENTS
l Pre-fertilization events include gametogenesis and gamete transfer.
l Much before the actual flower is seen on a plant, the decision that the plant is going to flower has taken place.
Several hormonal and structural changes are initiated which lead to the differentiation and further development
of the floral primordium. Inflorescences are formed which bear the floral buds and then the flowers. In the flower
the male and female reproductive structures, the androecium and the gynoecium differentiate and develop
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