Triploid cells might have an advantage in higher rates of protein synthesis,
leading to more rapid production of stored food in the endosperm. (And the
endosperm of some species is 5N.)
It is interesting to note that Gnetum gnemon does have double fertilization,
although this produces two embryos, not an endosperm-equivalent. (Carmichael
and Friedman. 1995. Am. J. Bot. 83: 767.)
David J. Hicks djhicks at manchester.edu
Biology Dept., Manchester College
