1921] JEFFREY & TORREY—HERBACEOUS ANGIOSPERMS 15 
shows the root of Ranunculus acris, The absence of secondary 
activities is striking. Sections through the subterranean perennial 
stem of the buttercup show leaf traces and root bundles in the 
axial region, both contrasting with the bundles of the stem proper 
by the entire absence of cambial activity. It is clear that in the 
buttercup the herbaceous habit has completely taken possession 
of both stem and root, so that secondary activities are equally 
conspicuous by their absence, both in strands destined to the 
leaves and to the roots. Even in the perennial and often rather 
thickened subterranean stem of R. acris, the fibrovascular tissues 
do not ordinarily show.themselves so well developed as to manifest 
the presence of typical foliar rays subtending the foliar traces. 
One can easily find such rays in the perennial subterranean 
stem of Thalictrum, however, and also in the aerial stem of various 
woody species of Clematis. It is obvious that typical foliar rays 
associated with distinctly woody perennial stems lie in the 
phylogenetic past of extremely herbaceous representatives of the 
Ranunculaceae, precisely as they do in the case of the more woody 
herbaceous types which ordinarily and likewise represent the Com- 
positae in temperate climates. : 
We may now pass to other illustrations of the herbaceous type 
as characterized by delicate stems and numerous leaf traces entering 
the stem at the node. The Umbelliferae will serve as our first 
illustration in this connection. Fig. 34 is a total transverse 
section of a node in the aerial axis of a species of Sanicula. Upper- 
most and toward the right is a leaf base in the act of fusing with 
the stem. It shows the presence of a considerable number: of 
foliar traces, which become still more numerous a little lower down 
by subdivisions of the original strands. Axillary to the foliar 
base is the cylinder of a lateral branch. This spreads out laterally 
over the surface of the main cylinder, in such a manner that the 
bundles of the branch present themselves to those of the main axis 
by their phloems. Fusion of these mutually confronting strands 
takes place in such a manner that a number of amphivasal strands 
results. The formation of these begins in the axillary region and 
proceeds progressively downward on either side. In fig. 35 appears 
a section somewhat lower down on the same axis as that shown 
