What forms the endosperm of a gymnosperm seed?

[Suraj M]

What forms the endosperm of a gymnosperm seed?? Some book said the 3 other macrospores which don't form the archegonia. I sthat right?
i just know that the stored food is transferred from the nucellus, but where does the diploid endosperm emerge from?

 

[jim mcnamara]

Primary endosperm (haploid tissue (n) ) is derived from the megagametophyte. The ontogenesis of primary endosperm is believed to derive from the megaprothallium in seed ferns. So, I do not know where your idea came from. See here:
http://www.seedbiology.de/evolution.asp#jurassic

 

[Suraj M]

oH . thanks for the link!
But what i don't still understand is that, the megagametophyte forms the prim. endosperm and also produces the archegonia!??

So, I do not know where your idea came from

Are you referring to the formation of endosperm from the rest of the 3 megaspores or that the food is transferred to the endosperm from the nucellus?

 

[jim mcnamara]

Endo sperm formation. Primary endosperm is haploid. It has to derive from mitosis. It has to derive from "neighboring" haploid tissue. That is the only point I'm making. The answer to your second question is: yes you understand correctly. It forms both.

Megagametogenesis in gynospermae: http://en.wikipedia.org/wiki/Megaspore