16 BULLETIN 1282, U. S. DEPARTMENT OF AGRICULTURE 
close resemblance exists among several varieties, attention is called 
to the fact in the descriptions. 
Allowance is made for a certain degree of variation, but satisfac- 
tory results should not be expected from the use of a few “ off- 
shaped ” nuts such as occur occasionally in all varieties, nor should 
results be expected to a certainty from the examination of only a 
few specimens. Best results will be secured when a number of aver- 
age nuts are taken from a fairly large sample, at least a pound. 
Whenever measurements and ratios are given, the eye should not be 
trusted, but the measurements should be actually made. 
In tracing down a variety it is not absolutely necessary to begin 
with the first characteristics given in the key. For example, the first 
division of the key, that of the slope of the base scar with reference 
to the axis, may be skipped and 
the prominence of the wing used 
as a starting point instead. This 
arrangement is useful when one 
is in doubt regarding a point in 
the series. On the other hand, the 
farther down the key one begins 
the more comparisons he will have 
to make. Only the standard rec- 
ognized varieties are given in this 
key. When a sample of nuts 
can not be traced in the key 
to any variety and is not found 
to agree with any of the de- 
scriptions, it may be classed 
with safety as a sample from 
a seedling tree which has not 
= 
been named or propagated com- 
Fi. 15.—_Diagram for use in Geieaniiie mercially. 
whether the base scar is descri as : : Sune 
sharply sloping or gently sloping: A brief explanation of the divi- 
“Sharply sloping’’ if the slope falls + 
within angie “A”: “gently sloping” i¢ SlOnS of the key and the terms 
the slope comes within angle “B.” used are here given. For other 
ae dotted line is at right angles to the definitions, see (a3 Explanation of 
terms.” 
The first divisions in the key are based on the various ways in 
which the stem scar slopes with relation to the longitudinal axis of 
the nut. The following six divisions are made: 

Va) 
x 
< 
A, Stem sear sharply dorsally sloping with reference to the axis (fig. 15); 
whole base also slopes dorsally. 
B. Stem sear slightly but distinetly dorsally sloping. (See diagram, fig. 15.) 
C. Stem scar at right angles to axis or slightly dorsally sloping when both 
of these types are found in the same variety. 
D. Stem sear at right angles to the axis or slightly ventrally sloping when 
both types are found in the same variety. Usually the majority of the 
nuts in a sample of this class have the stem sear at right angles to the 
axis. 
E. Stem sear at right angles to the axis or sloping slightly either ventrally or 
dorsally when all three types are found in the same variety. In this 
case a considerable percentage of the nuts will have the stem sear at right 
angles to the axis, while the number of nuts with the stem scar sloping 
dorsally or ventrally will vary. 
