Endosperm develops from the product of double fertilization or triple fusion in angiosperms. It provides nourishment for the developing embryo. Some seeds like pea and bean lack endosperm, while others like sunflower and coconut have persistent endosperm in the mature seed. Endosperm development depends on whether it is nuclear, cellular, or helobial. Fruits form as the ovary enlarges during embryo and endosperm development, with sepals and petals falling off and the ovary wall changing into the fruit pericarp.

1. POST FERTILIZATION CHANGES
DEVELOPMENT OF ENDOSPERM
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Endosper m is the nutritive tissue for nourishment
of developed embr yo.
In some angiosper m, the product of second
fer tilization or triple fusion is PEN.
It develops into endosper m.
In some cases it is absent such seeds are called
non endosper mic or ex -albuminous seeds e g. pea,
bean, grams etc.
In other angiosper m, endosper m per sists in
mature seeds and it suppor t the g r owth of embr yo,
such seeds ar e called endosper mic or albuminous
s e e d s e g . S u n f l o w e r, c a s t o r, c o c o n u t , m a i z e e t c

2. DEPEND ON THE MODE OF
DEVELOPMENT
Endosperm
Nuclear
endoperm
Cellular
endosperm
Helobial
endosperm

3. TYPE OF ENDOSPERM

4. DEVELOPMENT OF EMBRYO

5. FORMATION OF SEEDS AND FRUITS
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Simaltaneously with the development of embryo and endosperm, ovary
enlarges in size.
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Sepals, petals, stamens, style and stigma fall off and ovary changes into
fruit.
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Ovary wall change into pericarp (fruit wall).
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Pericarp initially is green and on ripening become
orange, red, purple, yellow etc.
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Each ovule in ovary also enlarge, outer integument become thick and
hard outer seed coat, called testa .
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Inner integument become thin, inner seed coat, called tegmen.

6. PARTHENOCARPY
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Mostly, the fruits are formed after fertilization
but there are some species in which fruits
develop without fertilization.
This is called parthenocarpy and such fruits are
called parthenocarpic fruits eg. Banana.

7. APOMIXIS AND POLYEMBRYONY
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Seeds are the product of fertilization.
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In some spices of grasses seeds are
produce without fertilization.
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This is called apomixis and such seed is
called apomictic seeds.
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Some nucellar cell near embryo sac start
dividing and develop many embryo this is
called polyembryony.

8. SIGNIFICANCE OF SEED
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The distribution and dominance of angiosperms on
earth is due to the seeds.
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Success of seeds as propogule is due to many
characters such as –
1.
2.
3.
4.
5.
6.
Dormancy
Viability
Reserve food
Protective coat
Dispersal
Edible fruits