vated species of oats are distinguished from their supposed 
wild ancestors by the absence of floret-articulation. This 
distinction is not only important taxonomically, but eco- 
nomically, as it facilitates harvesting the grain, and bio- 
logically, as it deprives the cultivated species of self- 
propagating ability and makes them dependent upon 
man for continued existence. The modes of inheritance 
of the floret-attachment type of the cultivated oats afford 
valuable criteria for evaluating the various theories on 
the origin of the cultivated species. 
Diploid and Tetraploid Species 
Jones (1940) made a study of the mode of inheritance of 
the floret-attachment types of diploid and tetraploid spe- 
cies. Four diploid crosses were made: A. Wiestii (wild) 
x A. strigosa brevis (cult.); A. Wiest A. strigosa; A. 
hirtula (wild) X A. strigosa brevis and Cc1795 (wild) x A. 
strigosa brevis. In each cross all individuals of the F; had 
the florets articulated, while the F2 segregation indicated 
the lack of articulation of the cultivated species to be due 
to two pairs of recessive factors. The genotype of the 
wild species for these factors was given as XX YY and 
that of A. strigosa as xxyy. 
In the tetraploid cross A. barbata (wild) XA. abyssin- 
ica (cult.) Jones found the F; to have all florets articu- 
lated, while the F2 segregation indicated the solid floret- 
attachment of A. abyssinica to be due to four pairs of 
recessive factors. The genotype of A. barbata was given 
as XX XXYYYY and that of 4. abyssinica as xxxxyyyy. 
Emme (1984) reported that in the F; of A. abyssinicaX 
A. Vaviloviana the wild-type attachment of the latter 
dominated. The F2 segregation was not given. 
The sterile triploid F, of 4. barbataX A. strigosa had 
the wild-type articulation (Nishiyama, 1929) as did the 
triploid F, of A.longiglumis XA. abyssinica (Jones, 1940). 
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