Manisuris spp. in the Andropogoneae. In the evolution- 
ary sequence leading to formation of the cupulate fruit 
case, tunicate glumes of maize are similar to the glumes 
of Mlyonurus tripsacoides (Galinat, 1956). 
Anatomically, tunicate glumes have all of the charac- 
teristics of a typical leaf-sheath, but on a reduced scale 
(Plate X, fig. 2). The close similarities of these organs 
may be enumerated as follows: (1) The inner (adaxial) 
and outer (abaxial) surfaces of tunicate glumes and leaf- 
sheaths are about equally pubescent with soft trichomes. 
This condition differs from that of the leaf-blade where 
pubescence is located chiefly on the upper (adaxial) epi- 
dermis and from that of the normal glume where the 
trichomes are confined to the lateral wings. (2) Both 
tunicate glumes and leaves (including sheath and blade) 
are herbaceous in texture because their mesophyll lacks 
the region of lignified cells which characterizes the nor- 
mal glume. (3) Stomatal development in tunicate glumes 
resembles that of the leaf-sheath and differs from the 
condition found in the normal glume. ‘Tunicate glumes 
and leaf-sheaths have well-developed stomata on both 
surfaces although they are more frequent and functional 
on the outer epidermis. As noted previously, if well- 
developed stomata occur in the normal glume, they are 
located on the inner surface. (4) The vascular system of 
tunicate glumes is more similar to the venation of leaves 
than it is to that of normal glumes. In both tunicate 
glumes and leaves, the anastomosing venation connects 
the principle bundles at irregular intervals along their 
entire length rather than just in the distal region as in 
the normal glume. (5) The structure of tunicate bundles 
is frequently identical to that of leaf bundles in contrast 
to the more reduced veins of normal glumes (Plate X, 
figs. 2 and 3). All of these anatomical comparisons sup- 
port the contention that the tunicate locus controls evo- 
[ 67] 
