ern maize. Another, a well-developed spathe, suggests 
the ancestral form not of maize but of Cow, whose fruit 
case has been found by Weatherwax (39) to comprise a 
spathe and a segment of the rachis. Corn grass probably 
is, as Galinat (8) has suggested, a ‘‘false’’ progenitor of 
maize, exhibiting certain traits which might have oc- 
curred in a remote ancestor of the Maydeae. 
Finally, the evidence from archaeological maize does 
not support the corn grass theory. Prehistoric maize had 
prominent glumes, but it did not have the long spathes 
of corn grass. The possibility that corn grass is the an- 
cestral form appears to us to be remote indeed. 
THE TEosinvTe THEORY 
The theory that maize originated as a domesticated 
form of teosinte—its nearest known relative— was first 
proposed by Ascherson (2). Later students, notably 
Harshberger (12) and Collins (6), modified the theory 
postulating that one parent of corn is teosinte and the 
other isa grass now unknown. As teosinte occurs natu- 
rally only in Mexico and Central America, supporters 
of this theory have usually assumed that both teosinte 
and maize originated in that region. We (21) concluded 
that teosinte is the progeny rather than the progenitor 
of maize — the product of the natural hybridization of 
maize and its wild relative, Tripsacum. ‘Teosinte, how- 
ever, plays an important role in the tripartite theory, for 
this theory holds that the many modern varieties of maize 
are the product of the introgression of teosinte into maize. 
Since 1989, new evidence has been presented both in 
support of and in contradiction to the teosinte theory. 
Beadle’s (4) discovery that the seeds of teosinte will 
*‘pop’’ when exposed to heat, shattering the hard, bony 
shell in which they are enclosed, shows one way in which 
teosinte might have been used as a food plant and weak- 
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