All of the morphological evidence supports Nickerson’s 
suggestion that the cupule (or, as proposed here, the 
lining of the cupule) represents a modified prophy]] which 
is adnate to the pistillate rachis. It appears that a modi- 
fication or elaboration of Sturtevant’s original definition 
of a cupule is necessary. Hereafter, we shall consider that 
the cupule of maize consists of both a mechanical com- 
pression groove and a prophyll which is adnate to it. 
Likewise, we shall also consider that in teosinte and 
Tripsacum the homologue of the cupule also consists of 
a rachis-segment depression which is lined with an ad- 
nate prophyll. Furthermore, it is apparent that it is the 
adnate-prophyll part of the cupulate fruit case which 
perfects this unique protective device. 
The pulvinus. Uf there are prophylls which are adnate 
to the pistillate inflorescence (ear) of maize, what is their 
role in the staminate inflorescence (tassel) which lacks 
cupules, and in the non-cupulate panicles of other grasses? 
It is suggested here that a homologue of the prophyl! in 
non-cupulate inflorescences including the maize tassel is 
represented by the axillary pulvinus. These pulvini, 
which occur in most paniculate grasses, are hairy swell- 
ings which are located in the axils of the primary branches 
of the inflorescence. The homology of the pulvinus and 
the prophyll, as suggested above, is supported by the 
following observations on maize inflorescences. 
(1) Pulvini and prophylls, either adnate or free, are 
mutually exclusive. 
(2) A series of intermediates between prophylls adnate 
to the main axis and pulvini in the axils of the 
pedicels of the spikelets may exist in the terminal 
and partly pistillate inflorescences of tillers. 
(3) The pulvinus is leaf-like in being a darker shade 
of green than the associated axis and is like the 
adnate-prophyll part of the cupule in shape, ex- 
treme hairiness and point of origin. 
[ 225 ] 
