More info about cotyledon: http://gened.emc.maricopa.edu/bio/bio181/BIOBK/dicotseed.gif

A text summary of the clickable map above, meant for web-crawlers and other automatic tools:
cotyledon two contained in seed of dicot
cotyledon develops into first leaf of embryo
cotyledon contains endosperm
cotyledon one contained in seed of monocot
cotyledon part of seed