Endosperm

The endosperm is a type of fabric of nutritive reserves of the Graine at the Angiospermes (plants with flower). At the time of the double fertilization, characteristic of Angiospermes, one of the spermatozoa (gamète male) will amalgamate with the two polar cores contents in the embryonic bag (endosperm is thus triploid), while the second spermatozoon will fertilize the Oosphère (gamète female) to form the embryo.

If the reserves (proteinic, lipidic and glucidic) are stored in endosperm, then it is bulky and the cotyledons (foliar outlines) are very thin: it is said that the seed is albuminous (case of the Ricinus). If on the contrary the reserves are in the cotyledons, the latter are bulky and there is no more endosperm: it is said that the seed is exalbuminée (case of Bean).

The equivalent (fabric évolutivement homologous) at the Gymnospermes still makes debate, it could be the Nucelle or a transformed supernumerary embryo.

One distinguishes four phases in the development from endosperm:

• the syncytial phase
• the phase of cellularisation
• the phase of differentiation
• cellular death

See too

• Seed
• double fertilization

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