A Classification of the Varieties of Cultivated Oats 123 
it under field conditions, the color of the young plant is of but minor 
importance in the classification of varieties, being generally useful only in 
their description. In the present work the color of the plant is employed 
as a supplementary character for identification only in the case of the 
variety Canadian, which exhibits at the time of full heading a distinct 
pale green color of sheaths, leaves, and glumes. 
As a feature of the general descriptions of varieties included in the 
present classification, the following color types have been observed: 
(1) Leaves dark green, slightly glaucous; sheaths dark green, very glau- 
cous, their general appearance being grayish green; glumes medium green, 
slightly glaucous. (Plate V.) (2) Leaves light green, often streaked and 
not uniform in color; sheaths medium green, glaucous; glumes bright 
green, barely glaucous. (Plate VI.) 
Before recording observations of color, it is necessary first to learn by 
careful inspection the different color types in the general mass; then, 
by selecting representative plants of each color type, the corresponding 
color of a given variety may be determined by comparison. In order 
to define color correctly the observation must be made during a calm, 
bright period, for in wind and shifting light accurate judgment of color 
is extremely difficult. It is also essential that colors should be always 
determined at a definite stage in the growth of the plant. Perhaps they 
may most accurately be judged at the time of full heading, that is, when 
the panicle has completely emerged from its sheath. An estimation of 
color at other periods of development will give different values: if earlier 
than the time of full heading, the bloom, a grayish covering of sheaths, 
leaves, and glumes, will not have fully developed and the color will be 
brighter; at a later time, the green color of all parts is being reduced as 
maturity approaches. 
SUMMARY 
In the classification of varieties of oats, the following characters are 
available for the distinction of main groups, or species, for the differentia- 
tion of subgroups, and for the identification and description of varieties: 
To distinguish A. nuda from A. sterilis, A. fatua, A. brevis, A. strigosa, A. sativa, and 
A. sativa orientalis. 
a. The free, or naked, caryopsis. 
To distinguish A. sterilis from the remaining species. 
b. The persistence of the upper grains to their rhachillas. 
