vinus, from these comparative studies. The bundles of 
both axes tend to be of two distinct diameters which are 
separated into two locations (a ‘‘meristele’’ arrange- 
ment). Those bundles with the smallest diameters lie 
adjacent to the rind or lignified periphery of the axis 
which, in the case of the (pistillate) rachis, is repeatedly 
parted into the wings of numerous cupules (Plate II, 
fig. 1). The bundles of the large diameter are scattered 
throughout the pith of the culm, but, in the rachis, they 
are usually concentrated near the margins of the pith, 
where they supply the longitudinal rows of traces to the 
lateral spikelets, even though a few ‘‘cauline’’ bundles 
may be isolated in the center of the pith. 
The diameter and position of an individual bundle is 
different in various parts of the plant. The larger trace- 
bundles, which extend horizontally from a leaf, curve 
downward from the leaf-node and then extend through 
about six internodes as they decrease in thickness and 
slope outward before connecting to the peripheral bun- 
dles. In the smaller trace-bundles, on the other hand, 
such connections occur progressively earlier in the de- 
scent, the smallest bundles remaining free for only one 
internode or less. As these leaf-traces descend, they sup- 
ply the axillary buds along the way by means of lateral 
connections to a network of horizontal bud-traces slightly 
above each leaf node. 
The glume cushions, which seem to be rudimentary 
leaves of the rachis, are vascularized by small bundles 
descending to the rind-bundles in the cupule wings be- 
low. Inasmuch as the apical end of these bundles con- 
nects with the vascular supply to the outer glumes of its 
axillary spikelets (Plate II, fig. 1) rather than terminat- 
ing as stubs, they would appear at first to be ‘‘rind- 
bundles”’; on the other hand, they could be rudimentary 
leaf-traces which have become folded inward and fused 
[9] 
