PANICLE CHARACTERS OF SORGO 23 
ences in form are consequently often difficult to indicate. For tl 
reason- and also because of alterations that result from fortuitous 
crossing which occasionally takes place in fields, it is frequently not 
possible to identify varieties with certainty solely by means of the 
s, although in some kinds the seed- show such plainly distinctive 
marks that one can be reasonably sure of the variety to which they 
belong. 
Form and minor features. — In apparently all varieties in early 
stages and until about the time the ovule is fertilized the pistils are 
Qtially straight and more or less regular in form and the styles 
are situated on a median plane, as evidenced by a lateral view: but 
as the carpels increase in size, and especially with the development 
of the endosperm in the ovule, the pistils commence to show diver- 
sity in form, this diversity persisting in the mature caryopsis. The 
differences in form are sometimes such that they are the more 
plainly seen when the caryopses are viewed dorsally. and sometimes 
they are more easily distinguished when viewed laterally. From a 
dorsal viewpoint an elliptic, ovate, obovate. suborbicular. or an in- 
termediate form may be apparent. Some of these forms are shown 
in Plates XIV and XV. These terms refer to the outline of the 
caryopsis from a dorsal viewpoint, being thus employed in the 
descriptions which are given in this bulletin. From a lateral view- 
point the differences primarily relate to whether the axis of the 
carpel remains essentially straight with the development of the pistil 
and inclosed ovule into the mature seed or whether it curves toward 
the ventral side at the summit or at the base. The summit may be 
either acute, obtuse, or subglobose. depending on the variety, but in 
certain varieties the axis becomes so curved that the summit, together 
with the styles, turns considerably in the ventral direction. In some 
cases also the styles become rotated toward the ventral side, so that 
their bases which persist on the mature grain can properly be described 
as being on the ventral half, as would be evident if a longitudinal 
section were made dividing it dorsoventrally. In certain varieties 
in which such curving of the pistil occurs, the scar. too. together 
with the short axis which sometimes remains attached to it. turns 
somewhat to the ventral side, and in some varieties the scutellum 
becomes curved and in others it is forced downward or forward. 
There are on the caryopsis two usually faint lines which extend up- 
ward from the scar past the edges of the scutellum to the bases of the 
styles. There is also sometimes a third line between these two. 
usually less distinct. These lines under high magnification are found 
to be strands of elongated cells associated with vascular 
The-e are associated with vascular bundles such as have been shown 
by Walker (17) and Schuster (15) to be present in the pistils 
sorghum and other grasses. From a taxonomic point of view i 
lines serve to show the extent of bending of the carpel and some- 
thing about its conformation at the base and the summit, but 
although various degrees of curving are to be seen in the varii 
sharp lines of distinction are usually not possible between the 
varieties in regard to them, there being forms more or less tran- 
sitional between those well marked. However, in the case of certain 
varieties: even where considerable fluctuation is evident, the tendencv 
