It includes –
1. Endosperm development
2. Embryo development
3. Ovules maturing into seed
4. Ovary maturing into fruit
ENDOSPERM-This is a product of triple fusion and develops from central cell of embryo sac. It is generally a triploid tissue. The cells of this tissue are filled with reserve food materials and are used for the nutrition of a developing embryo.
Mode of development of endosperm
1. Free nuclear endosperm development
2. Cellular mode of development
Example :-the coconut water from tender coconut is free nuclear endosperm which is made up of thousands of nuclei and the surrounding white kernel is the cellular endosperm.
FATE OF ENDOSPERM- Endosperm is meant for the nourishment of the embryo. There are two possibilities.
i) Endosperm is completely consumed during development of embryo before seed maturation. Such seeds are called as exalbuminous or non endospermic seeds. maturation.
Example: pea, beans, ground nut
ii) Endosperm persist in mature seeds such seeds are called albuminus or endospermic seeds. Example:- castor, coconut, rice, wheat, maize, barley, sunflower etc.
EMBRYONAL AXIS- it is the main axis of the embryo which divides it into different regions.
COTYLEDONS- It is an embryonic leaf in seed-bearing plants, one or more of which are the first leaves to appear from a germinating seed.It is termed as scutellum.
COLEORRHIZA-It is a sheath enclosing radicle and root cap.
COLEOPTILE- It is a sheath enclosing plumule.
PLUMULE- It is the part of a seed embryo that develops into the shoot
RADICLE- It is the first organ to appear when a seed germinates It grows downward into the soil.
EMBRYONAL AXIS- it is the main axis of the embryo which divides it into different regions.
COTYLEDONS- It is the first leaf that germinates. It is filled with stored food that the plant uses before it begins photosynthesis.
EPICOTYL- it is a part of embryonal axis present above the cotyledon. it terminates at the plumule.
HYPOCOTYL-it is a part of f embryonal axis present below the cotyledon. it terminates at the radicle.
RADICLE- root tip
PLUMULE-shoot tip
A fertilized ovule is called a seed. Seeds may be:-
1. ENDOSPERMIC/ALBUMINOUS SEED – example are wheat, maize, barley, sunflower, coconut, castor.
2. NON-ENDOSPERMIC/ EXALBUMINOUS- example are pea, bean, groundnut.
3. PERISPERMIC SEEDS- seeds in whichremains of nucellus is seen. The residual persistent nucellus is called perisperm examples -black pepper, beet, etc
Seed consists of:-
1. SEED COAT- it is formed from integuments of ovule its function is to give protection to the embryo. outer layer is made up of testa and inner layer is made up of tegmen. The micropylar as a small pore in the seed coat. This facilitate the entry of oxygen and water into seed during germination.
2. ENDOSPERM- present of a of absent
DORMANCY-It is a state of inactivity of embryo when the seed is not able to germinate. The moisture content of seed decrease and reaches 10-15%.
GERMINATION-The ability y of a seed to produce a seed to produce a seedling in presence of favourable environment condition like adequate moisture, oxygen and suitable temperature.
SEED VIABILITY- The period for which the seeds retain their power of germination is called seed viability. So some species live for several years and some seeds can remain alive for hundred of years.
A ripened ovary is called a fruit.
The wall of the ovary from the wall of the fruitwhich is called as pericarp.
Fruit may be :-
1. True fruit – fruits which develop from the ovary are called true fruits.
example: mango
2. FALSE FRUIT – fruits which develop from other floral parts and thalamus along with the development of ovary wall. example – apple, strawberry, cashew nut.
3.PARTHENOCARPIC FRUIT-when fruits develop without out the process of of fertilization. These fruits are seedless and can be produced through the application of growth hormone like auxins.
example- banana