What is endosperm? Describe the types of endosperm.

(N/A) The primary endosperm cell $(PEC)$ divides repeatedly to form a triploid endosperm tissue. The cells of this tissue are filled with reserve food materials and are used for the nutrition of the developing embryo. There are three types of endosperm: Nuclear,Cellular,and Helobial.
$(a)$ Nuclear endosperm: This is the most common type of endosperm development. The primary endosperm nucleus $(PEN)$ undergoes successive nuclear divisions without cytokinesis to give rise to free nuclei. This stage is called free nuclear endosperm.
$(b)$ Cellular endosperm: In this type,cell wall formation occurs after each nuclear division,making the endosperm cellular from the beginning.
$(c)$ Helobial endosperm: This is an intermediate type where the first division is followed by cytokinesis,resulting in a large micropylar chamber and a small chalazal chamber. Subsequent divisions in the micropylar chamber are usually nuclear.
Example: The coconut water from tender coconut is free nuclear endosperm (made up of thousands of nuclei),and the surrounding white kernel is the cellular endosperm.
Endosperm may either be completely consumed by the developing embryo (e.g.,pea,groundnut,beans) before seed maturation,or it may persist in the mature seed (e.g.,castor and coconut) and be used up during seed germination.