6 BOTANICAL GAZETTE [JANUARY 4 
The increase in complexity of the leaf-trace system over the condi- 
tion found in Avena, seems to be associated with the greater size 
of the leaf-sheath in Zea; just as a large stem generally has several 
circles of bundles, so a heavy leaf has a better developed bundle 4 
system. Most of the bundles in an aerial node of Zea are collateral, 
leaving out of consideration the swollen leaf-trace bundles. STRAS- 
BURGER (4, p. 348) finds amphivasal bundles at the point of origin 
of axillary buds and adventitious roots; I have confirmed his obser- 
vation in the former case. Much larger and more numerous amphi- 
vasal strands are however to be found in the nodes of the axillary 
branches bearing the ear of corn. One of these bundles is represented 5 1 
in fig. 5. It is only in the leafy part of the branch that these occur, j 
for in the “cob” the bundles are collateral, with an exceedingly well- . 
developed phloem, doubtless associated with the transfer of elabo- 
rated food. The amphivasal bundles of these branches are as usual 
bundle fusions, and their occurrence in the reproductive axis of a 
plant showing few elsewhere, seems to be a point of some significance, 
especially when we consider that Zea is probably a highly organized 
member of the family. 
Zizania aquatica merits special attention on account of certain 
features which may be regarded as primitive, e. g., the six stamens. 
In an aerial internode a narrow cortex surrounds the hollow central 
cylinder, and the two are separated by a ring of sclerified cells. 
Partly imbedded in this ring are a number of small bundles, some 
of which project into the cortex and on aceount of their origin must 
be regarded as cortical bundles. All the bundles are collateral, 
and those inside the sclerotic ring lie at different depths within the 
central cylinder. As would be expected from the aquatic habitat 
of the plant, the xylem is reduced; in fact, in some instances, it is 
represented only by a cavity, and in all cases it has its vessels very 
slightly lignified. The phloem does not share in this reduction. 
As the node is approached the bundles at the periphery of the central 
cylinder anastomose, at the same time becoming amphivasal, and 
a number of transverse strands join up some of the inner bundles 
of the stele with one another. At this level the leaf-trace bundles 
enter the stem; they are of at least three ranks, and of these the 
largest penetrate into the central cylinder, enlarging on the way; 
