notation was intended to designate a genom of Zea. We 
are, however, using it so ‘‘on the same notation’’ (Plate 
XLVI). 
Assuming then that Manisuris is one parent of Trip- 
sacum, one test of whether wild maize could be the other 
parent lies in a comparison of the recently discovered 
prehistoric wild maize to these other two grasses. Such 
comparisons were made by Mangelsdorf and Reeves 
(1939) in determining if teosinte might be a derivative 
from maize-Tripsacum hybridization, and by Sarkar and 
Stebbins (1956) in determining what characteristics the 
other putative parent of the tetraploid wheats must have 
possessed if EKinkorn were one parent. They found that 
Aegilops speltoides met virtually all of the requirements. 
Studies of this nature have been based on the general 
rule that, where an intermediate condition is possible, the 
presumed hybrid should show at least a tendency to be 
intermediate. 
An examination of Table I, which compares 18 of the 
important botanical characteristics which distinguish 
Manisuris, Tripsacum and Zea, shows that Tripsacum 
tencls to be intermediate in most cases where an interme- 
diate condition is possible. Some detailed consideration 
is needed, however, to explain the functional possibilities 
for intermediacy and one case of apparent evolutionary 
elaboration of a hybrid product. 
Monoecism is not only the definitive characteristic 
which separates Manisuris of the tribe Andropogoneae 
from Tripsacum of the tribe Maydeae, but it is also one 
of the few characteristics of Tripsacum which is non- 
intermediate between its putative parents. ‘The monoe- 
cism of Tripsacum could have come as a dominant trait 
from wild maize, as reconstructed from archaeological 
remains of this grass uncovered in the valley of ‘Tehua- 
cin in Mexico (Mangelsdorf et al, 1964) and illustrated 
[ 293 ] 
