PANICLE CHARACTERS OF SORGO 6 
tween minor forms. It will probably be found practicable for the 
growers to separate from the varieties now being grown a number 
of minor forms and to cultivate only those which, after being iso- 
lated, are found to be most desirable from the standpoints of yield, 
chemical composition, and the quality of the sirup produced. 
Varieties of sorghum, some of which belong to the sorgo group, 
have been described more or less completely by European and Amer- 
ican writers from pre-Linnean times until the present, the descrip- 
tions usually being more in detail where the number considered was 
large. Many of the characters which are presented here were em- 
ployed by some of these earlier writers. Possibly some of our va- 
rieties bear closer resemblance than these earlier kinds. However 
this may be, these earlier descriptions are not generally complete 
enough to serve as models for distinguishing ours, nor is it possible 
from the descriptions to identify with certainty many of these earlier 
kinds. However, some of them were evidently similar to present-day 
varieties and, presumably, were the same, although known by dif- 
ferent names. Some of the more recent descriptions of cultivated 
sorghums treating of both the sorgo and the grain-sorghum groups 
were given in greater detail than those published earlier, and some 
of the characters presented are useful in distinguishing varieties 
of the present time and in classifying them. 
It is the purpose to present in this bulletin the results of an in- 
vestigation of varietal characters in 30 or 40 kinds of sorgo grown 
by the Office of Sugar Plants of the Bureau of Plant Industry 
during the years 1918 to 1924, as well as to show points of simi- 
larity in groups of varieties. Only characters of the mature panicle 
are considered here. Although there are differences in regard 
to features of the stalks, branches, and leaves which it is hoped 
to present at another time, the greater number and somewhat more 
evident differences pertaining to form and structure of the mature 
panicle itself and to the form, structure, color, and pubescence of 
its axis, its branches, and the spikelets make the panicle of greater 
value for purposes of classification and identification than the vege- 
tative parts. The panicle also is the part most easily preserved. 
Although the direction of branches is likely to be somewhat changed 
when specimens are dried and some changes also take place with the 
advance in maturity of the growing plant, there are many characters 
which are approximately assumed some time before the seeds are 
mature, which change very little after maturity even in specimens 
dried for the herbarium. Xo attempt is made to present a key to 
varieties at this time, as it has not been possible to make a study of 
all of them, and no study has been made of the nonsaccharine group. 
For the purposes of this bulletin, the latter are distinguished from 
the sorgos by lack of juiciness and sweetness in the pith, this being 
in accordance with the general classification by Ball and Rothffeb 
W,P.17). 2 
REVIEW OF THE LITERATURE 
Types of both the saccharine and the grain sorghums, most of 
which it is to be presumed were taxonomic forms, have been de- 
2 The serial numbers (italic) in parentheses refer to "Literature cited," at the end of 
this bulletin. 
