tion. With condensation one internode or more may be 
so condensed that the spikelet pairs appear in whorls at 
one apparent node, as they do in much North American 
and in some Guarani maize (Figure 2 B), and the sessile 
and pedicellate spikelets retain the arrangement one 
ua 
Wess 
Lkihhe ,* Te 
wh TUR 
Ss 
~ 
QTE? 
at ld 
Lip ie 
Figure 2. Spikelet arrangement on tassel. 
would expect if a normal branch had been greatly short- 
ened. With multiplication, however, the arrangement is 
different, with the sessile and pedicellate spikelets alter- 
nating at the nodes as if the primordia had branched to 
give rise to more pairs of spikelets (Figure 2C). Spikelet- 
node index (‘Table I) may be defined as the average 
number of spikelet pairs per apparent node of the basal- 
[ 269 ] 
