The counts obtained by Nikolaewa on the polyploid 
species differ from those of all other workers and proba- 
bly represent errors. 
The case of A. Wiesti is a different matter. Emme 
(1980), working in conjunction with the taxonomist 
Mal’tsev, found 4. Wiesti to be a tetraploid, but stated 
that an oat from Palestine, which Vavilov said was essen- 
tially 4. Wiestii, was a diploid. The oat found by Spier 
(1934), Huskins (1927) and Dorsey (1925) to be diploid 
is described by Stanton and Dorsey (1927) and is said to 
have been received from Egypt. It also appears to be 
essentially 4. Wiestii except for usually having 9-nerved 
glumes. A. Wiestii sensu Mal’tsev has glumes with 7(8) 
nerves. Similarly 4. barbata may have both diploid and 
tetraploid forms. Jones (1940) reports having received 
many years ago, as an impurity in seed of 4. Wiesta, an 
oat which was identified as 4.barbata until Ellison (1938) 
found it to be a diploid. This diploid oat goes under the 
designation of Cc1795. Clearly more work is required 
before the relationships between the diploid and tetra- 
ploid species can be understood. 
Genome Analysis 
Although the chromosome numbers indicate certain 
Avena species to be polyploids, every cytologist and ge- 
neticist who has studied the polyploid species has found 
them to behave like diploids with complete bivalent for- 
mation at meiosis and high fertility. In discussing how 
this situation came about, Philp (1983) suggested the 
tetraploids may be auto- or allopolyploids arising from 
one or two diploid species, while the hexaploids probably 
arose from a tetraploid and a diploid and so ultimately 
may have been derived from two or three diploid species. 
The study of chromosome pairing at meiosis in the F1 
hybrids of interspecific Avena crosses has shed a certain 
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