23 
Phytogeny of the Cyperaceae. 
of them, from its very nature, must find attachment on the cauline system 
in order to be of any service in the economy of the plant. Accordingly 
the leaf-trace strands invest the cauline strands with a network of vascular 
elements, giving them an amphivasal character, which may be lost again in 
the internode by reorientation, or subdivision, as in the culms of the Glu- 
males, or which may persist throughout, as in the rhizomes of the Cyperaceae 
and in the subterranean stems of many Arales and Liliales. The whole 
matter may be summed up in the statement that among the Monocotyledons 
the leaf is the dominant organ in determining the characteristic stelar 
development. 
The Floral Axis. 
The inflorescence of the Cyperaceae, with a few exceptions such 
as Dulichitim and some Carices, is terminal upon the culm. It occurs 
in the form of a head, a spike, or a single or compound umbel. Camel’s (7) 
observations upon the structure and development of the floral organs 
indicate that there is in this subject a wide and interesting field for investi- 
gation. However, this matter is worthy of separate and special treatment, 
and we shall not attempt to consider it here. 
The particular fact to which we would direct present attention is 
the reduction in number and characteristic arrangement of the bundles 
in the floral axis. This axis arises from the terminal node of the culm, 
except in the cases mentioned above, where it is axillary. In case the 
leaves of the involucre are large, this node shows amphivasal bundles, which 
may even be continuous through the short internodes of the involucroid 
region, as in Cyperus strigosus ; but if the involucral scales are small or 
absent the bundles in the node are not amphivasal, as in Eleocharis. The 
bundles of the axis are seen to be continuous with the cauline system below 
the node. Passing upward in the axis these bundles quickly arrange them- 
selves in a single circle, from which strands are given off to the individual 
florets. Each floral trace arises from two adjacent strands of the cylinder, 
leaving the gap between them considerably wider as it passes off. On the 
way obliquely outward through the cortex the trace separates into two parts — 
an outer, slender strand, which is the trace of the subtending scale or glume ; 
and an inner, larger, double mass, which later breaks up into a circle of 
extremely delicate strands which pass to the floral organs proper. Fig. 20 
will serve to make these facts quite clear, so far as the structure of the 
central cylinder is concerned. It is to be observed that the bundles are 
here arranged in a single circle, and that there is no indication whatever of 
the amphivasal condition. There is a very remarkable uniformity in this 
respect throughout the entire Order. The structure prevailing in this region 
cannot fail to remind one of the arrangement already described as occurring 
in the young seedling of the Monocotyledons, and, in turn, of that present 
