Jobi exhibits variation in chromosome morphology be- 
tween populations in two features: (a) the extent of 
differential staining into eu- and heteropycnotic regions ; 
and (b) the numbers and positions on chromosomes of 
knobs which are present on the chromosomes of this 
species. The chromosomes of C. gigantea show differen- 
tial staining as in the case of C. aquatica and some popu- 
lations of C. Lachryma-Jobi. But they are devoid of 
knobs. Comparative chromosome morphology does not 
reflect the presence of the common genome (or genomes) 
detected by interspecific hybridization. 
Comparison of chromosome morphology does not 
show similarities between C. aquatica, species of Sorghum 
with a diploid chromosome number of 10, and maize: 
whereas some similarities are evident between the chro- 
mosomes of C. Lachryma-Jobi and those of maize. Data 
on genome analysis based on intergeneric hybridization 
between Coix, Sorghum, and maize are not available in 
order to interpret in genetic terms the morphological 
comparisons made in this study. 
[ 223 ] 
