A Classification of the Varieties of Cultivated Oats 101 
the types that may in some cases be used in identifying varieties. The 
classes arranged by Bohmer, however, are in some cases too finely differ- 
entiated for this purpose. 
In the description of all varieties, and occasionally for identifying those 
within small groups, the classes suggested by Broili and Fruwirth are 
used in the present classification, according to the following outline: 
Basal hairs present. 
1. Long. 
a. Few. 
b. Many. 
2. Short. 
a. Few. 
b. Many. 
Basal hairs absent. 
The presence of basal hairs may readily be observed, without magnifi- 
cation, in the mature grain. The hairs arc lost in threshing, however, 
and must be observed in the whole spikelet. 
Hairs of the rhachilla 
The rhachilla, or pedicel, is the secondary axis of the spikelet. It is a 
slender stalk borne at the base of the grain and articulating with the 
callus of the succeeding grain, and it often carries from a few to many 
short, setaceous hairs. The rhachillas of cultivated varieties of oats have 
been classified by Broili (1910) into several types according to their form 
and the frequency of their hairs. Denaiffe and Sirodot (1901), alone of 
the earlier investigators, have considered the character of the rhachilla 
in establishing the identity of varieties of oats, and they attach far greater 
importance to its hairiness than to its form. In the present work the 
hairs of the rhachilla are often used to distinguish varieties within small 
groups. They are partly destroyed by threshing, but may readily be 
observed, by a slight magnification, on the matured grain of the com- 
plete spikelet, and among several varieties they afford a reliable supple- 
mentary mark of identity. 
FORM OF THE RHACHILLA 
The rhachilla is variously flat, rounded, or furrowed. Its length, 
except in the extremely elongated spikelet of A. nuda, is usually 
