Tripsacum. The significant fact is that this introgression 
is not apparent in the lower strata. 
The fact that all glumes in the lowest stratum are 
glabrous may be of some significance. Cutler and Cutler 
(1948) report that hairs on the pistillate glumes are occa- 
sionally present in numbers proportional to those found 
on the leaf sheath. Insofar as glabrous pistillate glumes 
are associated with glabrous leaf sheaths, we may infer 
that the early Bat Cave corn was glabrous. Completely 
glabrous husks, found in Stratum II and described later, 
support this conclusion. 
The venation of the lower glume may be obscured 
because the glume is fleshy or because it is indurated as 
in teosinte. Both conditions are encountered in this ma- 
terial. Glumes on 90 percent of the ears in the lowest 
stratum show no venation because they are fleshy. In 
Stratum VI, however, the lack of venation occurs on 
both fleshy and indurated glumes. 
Upper Glumes. The upper pistillate glumes, easily 
studied on the exposed end of the lower half of a broken 
cob, possess several interesting characteristics. They vary 
in shape from those which resemble one end of a boat 
and have obviously once enclosed a kernel, to a short, stiff 
half-collar which once surrounded the base of a kernel. 
Forms intermediate between these two extremes are 
common. Boat-shaped upper glumes characteristic of 
true pod corn are found in all six strata, but are most com- 
mon in Stratum I. Collar-shaped glumes are most com- 
mon in Stratum V. 
The upper glume is most commonly membranaceous 
or chaffy, but may be fleshy, and, as in teosinte and Trip- 
sacum, even horny. All of the ears in the lowest stratum 
have chaffy upper glumes. Horny upper glumes occur 
only in Strata V and VI. 
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