Jeffrey and Torrey . — Transitional Herbaceous Dicotyledons . 243 
storage tissues, and the geometrical complexities which are indicated in the 
case of the stem do not present themselves. Moreover, since the root is 
a somewhat conservative organ, it, in many cases at least, indicates the 
primitive conditions of the herbaceous type of organization, characterized 
normally in both stem and root by large rays related to the appendages. 
The lower root in the figure is shown in tangential section, so that the very 
definite relation of the secondary root to a large storage ray in the main 
root can readily be made out. The conditions presented in this last item 
of oiir diagram could easily be duplicated for Clematis , T Italic trum^ and 
many other herbaceous representatives of the Ranales. Moreover, this is 
a situation of very wide occurrence in herbaceous forms of the most diverse 
systematic affinities. It is accordingly clear that, so far as the organization 
of typical herbaceous roots is concerned, the evidence is as conclusively 
against our critics as it is in the case of the axis. 
Text-fig. 5 is intended to show the topographical relations of leaf-trace 
and leaf-ray in an aerial axis of the genus Potentilla. The statement has 
been made, in the article to which we have been under the necessity of so 
often referring in the present pages, that only in the subterranean stem of 
the herbaceous representatives of the Rosaceae do the structures which we 
designate foliar rays occur. This assertion is unfortunately as devoid of 
foundation as are many of the statements of fact of our critics. Sangttisorba , 
Agrimonia , and Potentilla , as well as a number of other herbaceous Rosaceae, 
manifest clearly developed foliar rays in their aerial axes. The diagram 
shows the modifications in organization of the foliar ray in passing from the 
lower to the upper regions of the aerial stem. The cylinder is represented 
as cut away in the regions below three successive nodes. In the lowermost 
of these the foliar trace is shown on the margin of the medullary region. 
Here the leaf-trace is much smaller in its radial dimension than is the 
cylinder to which it belongs. It is related to a large amount of storage 
tissue, most abundantly developed outside the trace, but also flanking it on 
either side. The next level indicates a somewhat narrowed cylinder in 
which the foliar trace as a consequence bulks more largely in radial relation. 
As a necessary geometrical consequence of this situation the confronting 
portion of the foliar ray is considerably reduced. At the top of the figure 
appears the most slender aspect of the axis. Here the woody cylinder has 
on the one hand become reduced in thickness, and on the other the foliar 
trace has increased somewhat in radial development. These concurrent 
conditions lead automatically to the complete elimination of that portion 
of the foliar ray which lies radially external to the foliar trace. The 
flanking portions of the foliar ray, however, are still present, and represent 
the foliar storage provision for this region of the axis. 
R 2 
