● Following double fertilisation, events of endosperm and embryo `color{Violet}"development"`, `color{Violet}"maturation"` of ovule(s) into seed(s) and ovary into fruit, are collectively termed `color{Violet}"Post-fertilisation events"`.

`color{Brown}"ENDOSPERM"`

● Endosperm development `color{Violet}"precedes"` `color{Violet}"embryo"` development.

● The primary endosperm cell `color{Violet}"divides repeatedly"` and forms a `color{Violet}"triploid endosperm tissue"`.

● The cells of this tissue are filled with `color{Violet}"reserve food materials"` and are used for the `color{Violet}"nutrition"` of the developing embryo.

● In the most `color{Violet}"common type"` of endosperm development, the PEN undergoes `color{Violet}"successive nuclear divisions"` to give rise to `color{Violet}"free nuclei"`.

● This stage of endosperm development is called `color{Violet}"free-nuclear endosperm"`.

● Subsequently `color{Violet}"cell wal"`l formation occurs and the endosperm becomes `color{Violet}"cellular"`.

● The `color{Violet}"number"` of free nuclei formed `color{Violet}"before cellularisation"` varies greatly.

● The `color{Violet}"coconut water"` from tender coconut that you are familiar with, is nothing but `color{Violet}"free-nuclear endosperm"` (made up of thousands of nuclei) and the surrounding `color{Violet}"white kernel"` is the `color{Violet}"cellular endosperm"`.



● Endosperm may either be `color{Violet}"completely consumed"` by the developing embryo (e.g., pea, groundnut, beans) before seed maturation or it may `color{Violet}"persist"` in the mature seed (e.g. castor and coconut) and be `color{Violet}"used up"` during seed germination.

● Embryo develops at the `color{Violet}"micropylar end"` of the embryo sac where the `color{Violet}"zygote"` is situated.

● Most zygotes divide only after certain amount of `color{Violet}"endosperm is formed"`.

● This is an `color{Violet}"adaptation"` to provide `color{Violet}"assured nutrition"` to the developing embryo.

●Though the seeds differ greatly, the `color{Violet}"early stages"` of embryo development (embryogeny) are similar in both `color{Violet}"monocotyledons"` and `color{Violet}"dicotyledons"`.

● The zygote gives rise to the `color{Violet}"proembryo"` and subsequently to the `color{Violet}"globular"`, `color{Violet}"heart-shaped"` and `color{Violet}"mature"` embryo.

● A `color{Violet}"typical dicotyledonous"` embryo, consists of an `color{Violet}"embryonal axis"` and `color{Violet}"two cotyledons"`.

● The portion of embryonal axis `color{Violet}"above"` the level of cotyledons is the `color{Violet}"epicotyl"`, which terminates with the `color{Violet}"plumule"` or stem tip.

● The `color{Violet}"cylindrical portion"` below the level of cotyledons is `color{Violet}"hypocotyl"` that terminates at its lower end in the `color{Violet}"radical or root tip"`.

● The root tip is covered with a `color{Violet}"root cap"`.

● Embryos of `color{Violet}"monocotyledons"` possess only `color{Violet}"one cotyledon"`.

● In the `color{Violet}"grass family"` the cotyledon is called `color{Violet}"scutellum"` that is situated towards one side (`color{Violet}"lateral"`) of the embryonal axis.

● At its lower end, the embryonal axis has the `color{Violet}"radical and root cap"` enclosed in an undifferentiated sheath called `color{Violet}"coleorrhiza"`.

● The portion of the embryonal axis `color{Violet}"above the level"` of attachment of scutellum is the `color{Violet}"epicotyl"`.

● Epicotyl has a `color{Violet}"shoot apex"` and a few `color{Violet}"leaf primordia"` enclosed in a hollow foliar structure, the `color{Violet}"coleoptile"`.