opses larger than the smallest maize kernels. This ear of 
maize seems not to possess a single characteristic in which 
it is consistently unique. Its uniqueness lies rather in the 
particular combination of characters which it possesses. 
The fact that it is wholly pistillate, bears large caryopses 
ona massive rachis and is a strongly compacted inflores- 
cence, readily distinguishes it from all other grass inflo- 
rescences. 
Of these characteristics the last, compaction, is by no 
means the least important. Once this fact is recognized 
—that the ear of maize is one of the most strongly com- 
pacted of all inflorescences—then much of the mystery 
which has surrounded the ear disappears and it becomes 
scarcely more difficult to understand than a head of cab- 
bage which also is a strongly compacted but otherwise 
relatively simple structure. 
The second type of maize ear, the type which presum- 
ably results from ‘Tripsacum-contamination is, like the 
first, a compact spike. It differs from ‘‘pure’’ maize pri- 
marily in having a spiral rather than a whorled phyllo- 
taxy and asystematic rather than a random arrangement 
of sessile and pedicellate spikelets. Indeed a brief de- 
scription would appropriately term the first ‘‘whorled- 
random’’; the second ‘‘spiral-systematic.’” But there 
are other differences as well. The tissues of the rachis 
and glumes of the spiral-systematic type are usually in- 
durated ; the rachis as a whole being quite tough, though 
evidence of an inherent rachis fragility is sometimes dis- 
cernible. The rows of grain are distinct and not infre- 
quently separated in pairs. When this occurs a pair of 
rows is the equivalent of a row of paired spikelets. The 
tendency for a rigid vertical alignment of the spikelets 
is so strong, probably as the result of an inflexible spiral 
phyllotaxy, that ears in which the number of pairs of 
rows is odd are in the minority and are usually twisted. 
[ 70 | 
