90 
W. C. Etheridge 
other hand, forms that are closely related structurally may be placed in 
widely different groups on the basis of variation, induced by environment, 
in the weight and kernel content of their grains. The system, while prob- 
ably useful in grading the quality of grain, is of little use for the perma- 
nent classification and identification of varieties. 
Denaiffe and Sirodot (1901), in their studies of the cultivated oats of 
France, have distinguished 76 varieties. The main groups of varieties 
arranged by these authors are characterized by the form of panicles, and 
by the color, form, and size of grains. The form of panicles, however, is 
used only in the minute descriptions of individual varieties and does not 
appear in the following system for the identification of varieties, here 
rearranged from the original diagrammatic outline: 
I. Grains white, white-yellowish, or yellow. 
A. Duckbill grains, plump, open-pointed; bmma flattened, very white. 
B. Outer grains 12-14 mm. long; numerous 1 -grained spikelets; rhachilla nail- 
headed, fine, long; grains double. 
C. 2-grained spikelets predominant; 1-grained spikelets numerous; grains 
very duckbill-like. 
D. Grains barley-like, 13-14 mm. long, variable, large, plump; lemma 
extremely flat; 1000 grains weigh 38-42 grams. 
DD. Small barley-like grains; outer grains 12 mm. long, duckbill-like, and 
often bearded; single grains large; 1000 grains weigh 34-35 grams. 
CC. 1-grained spikelets predominant; grains of the intermediate barley-like 
type; outer grains 13.5-14.5 mm. long, variable; single grains less plump 
and longer; 1000 grains weigh 38-42 grams. 
BB. Outer grains 15-16 mm. long, large, plump, swollen, large-pointed, and 
duckbill-like; 1-grained spikelets not occurring; awn usually present and 
geniculate; rhachilla flat, short, and hairy at the summit; 1000 grains 
weigh 47-49 grams. 
AA. Grains not plump, slightly spreading at the point, rather slender; lemma convex, 
white, white-yellowish, or yellow; no double grains. 
B. Grains medium-sized, swollen and full, yellowish, rarely very yellow, 
variable; rhachilla 2 mm. long, and with 2 furrows; 1000 grains weigh 
40-46 grams. 
C. Outer grains 14-15 mm. long, slightly plump, medium full; palea rather 
large at point; lemma convex; 1000 grains weigh 43-46 grams. 
CC. Outer grains 15-16 mm. long, not plump, scarcely full; lemma generally 
flattened; palea rather pointed; 1000 grains weigh 40-43 grams. 
BB. Grains small, slightly swollen and slender; rhachilla fine, 3 mm. long, without 
furrows, nail-headed; 1000 grains weigh 34-39 grams. 
C. Grains white or slightly yellowish. 
D. Grains white-yellowish, variable, intermediate in size; base of the 
grain with lips of the scar unequal; 1-grained spikelets not 
occurring. 
DD. Grains white, narrow, slender, small, often bearded; base of the grain 
small and straight, with lips of the scar almost equal; 1-grained 
spikelets numerous. 
