plant of Coroico maize had twenty nearly equal tillers 
and many plants had five or more. Although all these 
tillers were basal, one may consider these plants as tend- 
ing to branch from the stem, for the shanks of the ears 
were greatly elongated on many plants. Seedlings and 
very young plants of Coroico maize have laterally flat- 
tened culms, as compared with the terete ones of most 
other types. This resembles some grasses and probably 
is correlated with tillering. 
Leaves vary in shape, but it is difficult to measure 
them rapidly and to make comparison. Coroico leaves 
are more slender than those of the highland types, have a 
deeper channel over the midrib and the sheath is pubes- 
cent. Guarani maize has hairs along the edges and the 
upper part of the sheath, while highland maize usually 
has very little hair restricted to the edges near the auri- 
cles or may be practically glabrous. 
The Tassel 
Tassel branches are fairly constant in number for each 
race and, although unfavorable environmental conditions 
may reduce the number of branches, the reduction usual- 
ly is within the range of the race. Fasciation may increase 
the number of branches just as it affects the number of 
spikelet pairs at a node and this has probably been the 
cause of the high number of branches in Bolivian sugar 
corn tassels (Figure 1 I), double that of other maize of 
the same race. The series of diagrams of typical tassels 
(Figure 1) shows that there is great difference in the 
number of branches, their length and points of origin. 
Sterile Zone is aterm employed for the distance meas- 
Figure I (shown on opposite page). Tassel diagrams. A. Coroico maize. 
B. Guarani maize. C. Altiplano maize. D. Uchukilla maize. EK. Valle 
maize (morocho or huilcaparo). F. Valle maize (chuspillo or sweet). 
G. Cuzco maize. 
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