100 
W. C. Etheridge 
ing the flower in the grasses. In many wild species of Avena the lemma 
is more or less densely hairy, and the specific character of the hairs them- 
selves is in some cases a mark of distinction. Among cultivated forms, 
however, the lemma is usually glabrous, and it is only in rare instances 
that a variety is distinguished by hairs on this part of the grain. 
The callus, a somewhat swollen callosity at the base of the lemma, 
is an insignificant part of the oats grain, but it often bears more or less 
conspicuous bristles, conveniently called basal hairs, which are in some 
cases an important feature in the description of varieties and useful in 
establishing their identity. Indeed, the basal hairs are frequently 
employed by botanists, notably Hitchcock (1908) and Britton and Brown 
(1896), in characterizing Avena species. Denaiffe and Sirodot (1901) 
are the only authors who have specifically named the basal hairs in classi- 
fying cultivated forms of Avena; although Bohmer (1911), Broili (1910), 
and Fruwirth (1907) have mentioned this character in discussing the 
morphology of the oats grain, and have distinguished the following types 
of basal hairs on the basis of difference in their form and frequency: 
1. Numerous to bushy short bristles. 
2. Few short bristles. 
3. Numerous long, fine, bushy bristles. 
4. Few long, fine bristles. 
5. Bristles almost wholly absent. 
6. Bristles numerous, irregular, lon^, and finf 
7. Bristles long and fine. 
1. Single short hairs. 
2. Many short, bristly hairs. 
3. Single long hairs. 
4. Many long, bushy hairs. 
5. Single twisted nnd band-like hairs. 
Hairs of the callus 
Bohmer 
Broili 
Fruwirth 
1. 
2. 
3. 
4. 
Hairs very long and numerous. 
Hairs very long, but few or scarce. 
Hairs short, few to many. 
Hairs short, occurring singly. 
The classes of Fruwirth, and those of Broili with the exception of the 
fifth, which has not been observed in the present work, adequately define 
