A Classification of the Varieties of Cultivated Oats 127 
or rhachilla, itself (Plate I, 1). The basilar connection of the lower grain, 
however, is like that of other wild forms, such as A. fatua. 
Cultivated varieties of A . sterilis retain to a marked extent the character 
of the basilar connections of the wild forms. Their upper grains do not 
separate from their rhachilias, while between the lower grain and its 
peduncle the lines of articulation are still evident. Another distinction of 
cultivated A. sterilis forms is the elongated caryopsis, this being of greater 
length than in most other varieties. (Plate II, 1, and fig. 12.) 
The cultivated forms of A. sterilis are widely distributed. They are 
the principal oats of the whole Mediterranean region, the main groups 
being A, sterilis byzantina and A. sterilis algeriensis. In the United 
States also the A. sterilis forms are widely cultivated, the well-known 
varieties Red Rustproof and Burt being the principal representatives. 
The following description covers the cultivated forms of A. sterilis: 
Culms spreading or semi-erect in early growth, fine and stiff; leaves 
narrow; panicles equilateral; glumes usually longer than in the other 
cultivated groups; awn usually present on the outer grain and frequently 
on the inner grain; basal hairs usually present; basilar articulation of the 
outer grain evident; rhachilla of the outer grain shorter than in most 
other cultivated forms, while the rhachilla of either the outer or the 
inner grain is so solidified with the callus of the succeeding grain that 
the parts do not separate without tearing away the rhachilla itself; cary- 
opsis more elongate than in most other cultivated groups. 
Key to varieties 
A. Grains dark-colored, brown or black. page 
B. Grains black; awn usually present on both tWe outer and the inner grain 
A. sterilis nigra. 127 
BB. Grains brown to brownish black; awn seldom present on the inner grain 
Sterilis Selection. 129 
AA. Grains light-colored, yellow or brownish yellow. 
B. Plants spreading in early growth; basal hairs long (3-6 mm.) . .Red Rustproof. 129 
BB. Plants semi-erect in early growth; basal hairs short (1-2.5 mm.) or wanting. 
C. Basal hairs present; basilar articulation of outer grain evident; grains dull 
yellow. Burt. 129 
CC. Basal hairs wanting or seldom present; basilar articulation of outer grain 
usually solidified; grains dun-colored King. 130 
Descriptions of varieties 
Avena sterilis nigra (Plate VIII, 1, and fig. 22). — Culms spreading in early 
growth, fine, stiff, glabrous or sparsely haired near the nodes; sheaths dark 
