1921] JEFFREY & TORREY—HERBACEOUS ANGIOSPERMS 9 
concurrent transformation of their separating fibers and vessels into 
storage elements. This results in the final formation of a large 
homogeneous complex of radial storage tissue, intimately connected 
both topographically’ and physiologically with the leaf trace. 
Fig. 12 shows also the leaf trace enlarged to the same proportionate 
size as the huge storage ray to which it belongs. 
It is clear from the comparison of the foliar rays in the species of 
sunflower that the size of the ray, the size of the leaf trace, and the 
degree of parenchymatous homogeneity of the foliar ray, all directly 
correspond to the degree of herbaceous development of the species. 
Helianthus annuus, which is not only the most herbaceous of the 
three, but is of such vigor as to be able to proceed from seed to 
seed in a single season, is characterized by marked superiority in 
all three particulars. Fig. 13, showing the structure of the leaf 
ray of H. annuus under the same enhanced magnification as the 
other two species in figs. 9 and 14, makes it clear that the structure 
of the foliar ray in the former species is characterized by enough 
variety in the dimensions of its constituent elements to reveal its 
composite derivation from the modification of wood rays, fibers, 
and vessels. 
Having made a comparative study of the foliar ray in progres- 
sively more herbaceous species of Helianthus in the lower region 
of the aerial stem, attention may be given now to the considerations 
represented in the upper nodes of the axis. Fig. 15 illustrates the 
outstanding leaf trace of an-upper node of the stem of H. tuberosus. 
It is separated from the stem bundles on either side by flanking 
parenchymatous bands of the foliar ray. The large radial extension 
of the foliar ray which marks its organization in the lowest part of 
the stem has become progressively reduced in the region of higher 
nodes, until at. the level of fig. 15 it has entirely disappeared. 
This simple geometrical condition has been diagrammed recently 
by Wuitaker (7) and need not be further considered here. 
Another feature of interest, which is particularly obvious in 
the upper nodes, is the condition of cambial activity in the foliar 
and ¢auline bundles respectively. Fig. 16 represents the stem or 
“common” bundle immediately to the right of the foliar trace in 
fig. 15. Above is to be seen the fibrous pericycle of the bundle 
