A Classification of the Varieties of Cultivated Oats 125 
ters; for most characters of cultivated plants have become more or less 
modified under cultivation, and many of them, although distinct in wild 
forms, no longer afford reliable marks of identity for cultivated varieties. 
They cannot be traced through the complexity of cultivated forms; their 
distinctiveness gradually disappears under the ameliorative influence of 
cultivation, and is at times inhibited by the presence of factors introduced 
through hybridization. Hence, with the exception of a few specific 
differences, the characters available for classification of the varieties of 
any crop are more or less transitional, and few of them are alone sufficient 
to establish the identity of a given variety. Therefore the sum of many 
slight differences must be employed, and by such accumulation the small 
subgroups, and finally the individuals, may be distinguished. 
CLASSIFICATION OF GROUPS 
The principal cultivated varieties of oats, together with their basic 
wild species, may be classified as eight more or less distinct groups, accord- 
ing to the following outline : 
PAGE 
A. Kernel loose within the surrounding hull ; lemma and glumes alike in texture 
Avena nuda. 125 
AA. Kernel firmly clasped by the hull; lemma and glumes different in texture. 
B. Upper grains persistent to their rhachillas Avena ster His. 126 
BB. Upper grains easily separating from their rhachillas. 
C. Lemma extended as teeth or awn points. 
D. Lemma with 4 teeth or awn points Avena abyssinica. 130 
DD. Lemma with 2 teeth or awn points. 
E. Lemma elongate, lanceolate, with distinct awn points 
Avena strigosa. 130 
EE. Lemma short, abrupt, blunt, rather toothed than awn-pointed 
Avena brevis. 130 
CC. Lemma without teeth or awn points. 
D. Basilar connections of the grains articulate Avena fatua. 131 
DD. Basilar connections of the grains solidified. 
E. Panicles roughly equilateral, spreading Avena sativa. 132 
EE. Panicles unilateral, appresssd Avena sativa orientalis. 154 
AVENA NUDA 
Avena nuda differs from all other species of Avena by three remarkable 
characters: (1) the lemma and the palea do not clasp the kernel as in other 
forms, and the kernel is therefore loose, or free, within the hull; (2) the 
rhachillas of the three- to many-grained spikelet are so elongate that the 
uppermost grains are borne above the glumes; and (3) the glumes 
