cream-colored, firm, quite stiff and possess moderate 
pith cavities and alveoles, some characters, especially in 
those ears from Santa Cruz Province on the southeastern 
Bolivian border, suggest Coroico maize. The grains in 
Santa Cruz Province are smaller, so strongly tesselated 
at times that the pairs almost overlap, and a dominant 
aleurone color inhibitor is found in most ears. 
There are two types of Guarani maize, grown for sep- 
arate purposes and planted separately: yellow soft flour, 
‘alled abati moroti, and crystal-white flint, called abati 
tupi. The yellow color of the flour maize is formed by 
a brown aleurone, other colors being absent when the 
dominant color inhibitor is present. The flour types ap- 
pear to be the older form. The ears of flint are stiffer, 
more ligneous, more cylindrical; the alveoli are deeply 
sunk into the cob, and the grains are rounded at the top, 
less flattened and less compressed by the husks. 
The apparent uniformity of Guarani maize must not 
be interpreted as a lack of potential variation. Concealed 
within this race, in part by modifiers and inhibitors and 
by human selection of two definite varieties, is an amaz- 
ing amount of potential variation. From selected Guarani 
ears it might be possible to develop many of the varieties 
of South American highland maize and still have some 
characters which are not found in other varieties. 
Coastal Tropical Flint 
The orange-yellow tropical flint which is the most 
common maize in Kurope, Cuba and throughout the 
Caribbean area, is also found in eastern Ecuador, Brazil 
and Argentina. This variety belongs to the race of trop- 
ical flints described by Anderson and Cutler (1942) and 
probably has been spread by the Arawak, Carib and ‘Tupi- 
Guarani groups which populated coastal areas from Cuba 
to Argentina. In Brazil, where it is called Cateto, it was 
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