et al. (1946). The spikelets of Bond shatter readily. 
Coffman et al. (1925) made an extensive study of vari- 
ability in A. byzantina cultivar Burt and found a most 
confusing array of forms. Some plants had the lower 
floret (spikelet) articulated while others did not. In some 
plants the rachilla segment when fractured remained with 
the floret above, in others it remained with the floret 
below, while in still others it fractured near the middle, 
parts remaining with both florets. 
Mal’tsev (1929) and Mordvinkina (1936) state that all 
the florets of 4. byzantina are non-articulate, while the 
latter author is able to distinguish between the grains of 
A. sativaand A. byzantina by the angle of the fracture- 
surface of the lower florets. If his 4. byzantina has the 
C-factor, the difference between it and A. sativa might 
be due to the C-factor being superimposed on the differ- 
ent genetic backgrounds of the two species. The alterna- 
tive is that non-articulate florets in many varieties of 4. 
byzantina are due to other genetic factors than the C- 
factor. Clearly more information is needed before defi- 
nite conclusions can be drawn. 
Avena fatua 
The genetic evidence indicates that the factors govern- 
ing complete floret-articulation of the wild oats are in- 
hibited by the B- and C-factors. It is sometimes assumed 
that the articulation factors of A. fatua are located ona 
single chromosome which is called the B-chromosome. 
There is no evidence for this, it being probable that many 
factors on many chromosomes are responsible for the 
grain characters of 4. fatua. 
It is generally believed that 4. fatwa is the progenitor 
of A. sativa and, as stated earlier, their parallel variation 
and geographic distribution speak for a close relationship 
between the two. However, no one has observed any 
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