strain of A. fatua to mutate to A. sativa. Vavilov (1926) 
noted that no attempt to cultivate 4. fatwa would in- 
duce it to lose its brittle manner of floret-attachment. 
Coffman (1946),stated that, despite the fact that 4. fatua 
isacommon weed of fields and fence rows in the western 
United States, there is no evidence of any cultivated 
form having arisen from it. 
On the other hand, both A. byzantina and A. sativa 
have given rise to fatuoids resembling A. fatua, and 
Coffman (1946) stated that he was inclined to believe the 
origin of 4. fatua paralleled that of the fatuoids. Ear- 
lier (1936) Stanton wrote: ‘‘T’o one with imagination, the 
occurrence of fatuoids might be considered a provision 
of nature to return cultivated oats to wild forms, thus 
making them self-propagating in case, through some dis- 
aster, the cultivated forms were no longer in the hands 
of human beings. ”’ 
If it is true that 4. fatwa arose from cultivated oats 
and if all cultivated oats arose from A. sterilis and if the 
cultivated oats are not self-propagating, then 4. byzan- 
tina, A. sativa and A. fatua, including a total of eleven 
subspecies, have evolved within the period of man’s agri- 
cultural activities. This would be exceedingly explosive 
evolution. 
Conclusions 
The evidence from genetics indicates that the lack of 
floret-articulation of the diploid and tetraploid cultivated 
oats is due to different genetic factors than the similar 
character of the hexaploid cultivated species. It may be 
concluded that different evolutionary forces have pro- 
duced similar results in the two subsections. Although it 
seems probable that recessive mutations and geographic 
isolation have produced the diploid and tetraploid culti- 
vated species, the mode of origin of the hexaploid cul- 
tivated oats is by no means clear. The final decision on 
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