Nikolaus Foidl, October, 2009
Recent literature suggest that the split from a common ancestor between rice and the ancestor of maize happened some 45 to 60 million years ago. Maize was formed from teosinte as a common ancestor. Sorghum apparently split from the common ancestor with maize sometimes between 16.6 and 11.9 million years ago.
If the environment is overcharging the abilities of the gene set, then the plant seems simply to split up in different lines of development (??), although keeping the, during evolution silenced gene sets, or inactivated subprograms.