Endosperm is a highly nutritive tissue which provides nourishment to the developing embryo.
Endosperm development precedes embryo development. The primary endosperm nucleus undergoes a series of division and ultimately forms endosperm.
In plants like beans, Peas, groundnut, etc., the entire endosperm is consumed in the nutrition of the developing embryo.
Types Of Endosperm
On the basis of development, three types of endosperm have been recognised:-
- Nuclear endosperm
- Cellular endosperm
- Helobial endosperm
1) Nuclear Endosperm
This type of endosperm commonly occurs in polypetalous dicotyledon. In the development of Nuclear endosperm, the first few division of the primary endosperm nucleus are not accompanied by cell wall formation and nuclei thus produced remain free in the cytoplasm of the embryo sac.
Wall formation takes place subsequently or the nuclei remain free indefinitely.
Cocos nucifera is a classic example of nuclear endosperm. The watery liquid endosperm which fills the large embryo sac contains numerous free nuclei. It is known as liquid syncytium.
The watery endosperm of coconut contains growth promoting ‘coconut milk factor‘ and that is why it is used as a nutrient medium in culture experiments.
Examples of Nuclear Endosperm
- Glycine max
- Arachis hypogaea
- Cocos nucifera
Also Read : – Pollination and its types
2) Cellular Endosperm
This type of endosperm formation commonly occurs in gamopetalous dicotyledons.
In the development of cellular endosperm, wall formation commences with the first division of the primary endosperm nucleus.
The first wall is usually laid down transversally, but the subsequent division are irregular. This result in the formation of endosperm tissue where cells do not show any regular arrangements.
Examples of Cellular Endosperm
3) Helobial Endosperm
This type of endosperm, intermediate between the nuclear and cellular type, occurs in the member of the order halobiae.
The first division of the primary endosperm nucleus is accompanied by the formation of a transverse wall.
This divides the embryo sac unequally into a small Chalazal chamber and a large micropylar chamber. It is followed by free nuclear division in both chambers. But there are relatively few division in the Chalazal chamber and this region often degenerates.
The free nuclear division in the micropylar chamber are usually followed by wall formation and thus a cellular endosperm tissue is formed.
Examples of Halobial Endosperm
FAQ’s Regarding Endosperm
What are the three types of endosperm?
The three types of endosperm are :
- Nuclear Endosperm
- Cellular Endosperm
- Helobial Endosperm
Is coconut A Helobial?
No, Coconut comes in nuclear endosperm.
Which is the most common type of endosperm?
This type of endosperm commonly occur in polypetalous dicotyledons.
What is liquid syncytium in coconut?
The watery liquid endosperm which fills the large embryo sac contains numerous free nuclei. It is known as liquid syncytium.
What is endosperm culture?
Endosperm culture are the nutritive layer on which other experimental plants are grown. Most Common endosperm culture example is coconut water.