lution from the primitive foliaceous state which is typi- 
cal of glumes in general to the highly specialized glumes 
of modern maize. 
Vestigial glumes. The vestigial glume (Vg) mutant re- 
ported by Sprague (1989) is of particular morphological 
and agronomic significance. Originally this naked- 
flowered character was thought to be of no economic 
value because it was associated with pollen-blasting tas- 
sels. The discovery of modifying genes which usually 
permit abundant pollen production in Vg tassels, aroused 
interest in the utilization of the Ve character to improve 
the structure of the sweet corn (maize) ear (Galinat, 
1951, 1953). It became apparent, however, that in order 
to insure pollen-production in inbred lines grown under 
various environmental conditions, it would be necessary 
to have tassels with glumes of normal length on Vg 
plants bearing glumeless ears. This desired Vg pheno- 
type became a reality after a certain weak tunicate allele 
derived from the race ‘‘Chapalote’’ was combined with 
the Vg gene (Galinat, 1955, 1957). As a result, the 
agronomic development and testing of sweet corn hybrids 
with this new Vg phenotype is now in progress. 
Vg glumes deviate from normal in the opposite direc- 
tion from the deviation of tunicate glumes (Plates [X 
and X, figs. 2, 3, 4). In comparison to normal ones, Vg 
glumes are thicker, shorter and have increased lignifica- 
tion, while 7’ glumes are thinner, longer and _ have re- 
duced lignification (lacking the lignified region in the 
mesophyll). The progressive thickening of glumes in 
this series of three types (7'u; normal; Vg) appears to 
result largely from the development and proliferation of 
many small lignified cells in a region just under the ab- 
axial epidermis. The smaller the cell in this region, the 
thicker the deposit of lignin in the secondary wall (Plate 
X1). 
[ 68 | 
