Endosperm is a nutritive tissue for the developing embryo.
In Gymnosperms endosperm is diploid and formed before fertilization.
while in angiosperm the endosperm triploid and formed after fertilization.
The endosperm in angiosperm is generally a product of these fused nuclei ( i.e one male nucleus and two polar nuclei ).
TYPES OF ENDOSPERM
Nuclear endosperm
Cellular endosperm
Helobial endosperm
NUCLEAR ENDOSPERM
In this type after the first division several nuclei are formed but cell wall not formed. The nuclei may be either remain afree or may be seprate by wall formation and vacuole is formed.
These nuclei specially present at the micropylar and chalazal ends of the embryosac.
These nuclei form isolated group called nodules.
After free nuclear division cell wall formation started.
Normally cell wall formation started towards periphery towards centres.
e.g. Coconut( Cocus nucifera )
CELLULAR ENDOSPERM
In this type of endosperm the division takes place by cell wall formation and embryo is divided into several chamber.
The first division usually transverse but some verticle or oblique.
Cellular endosperm type mostly found in dicotyledons.
HELOBIAL
This type is intermediate between cellular and nuclear type.
It is found commonly among monocotyledons.
In this type the first divisionto is followed by a wall formation divided the embryosac in two chamber the micropylar and chalazal end.
The micropylar chamber usually larger than chalazal chamber.
