368 KANSAS UNIVERSITY SCIENCE BULLETIN. 
All of these cells are well adapted for storage, and many are 
packed with well-formed starch grains while others contain 
large crystals of calcium oxalate. Tannin is abundant 
throughout the medulla. 
THE ROOT. 
In making this investigation, roots young enough to show 
primary structures were not obtainable, and as in all speci- 
mens the main root was too large to section and illustrate as 
a whole, it was necessary to select secondary roots for study. 
These, however, were found to have their tissues in structure 
and drrangement almost identical with those of the main root. 
In transverse section, a root shows a broad bark surrounding 
a circular xylem (fig. 4, plate II). 
The brownish-red cork is developed in regular radial rows, 
and becomes scaly and dark brown on the exterior (figs. 30 
and 35, plate VI). Lying between the phloém and phellogen 
is a broad zone of parenchyma cells interspersed with bast 
fibers (fig. 4, plate II). These fibers are similar to those of 
the stem, but differ in being shorter, slightly broader, and 
more irregular in form. They vary from 8 to 20 microns in 
breadth and from 400 to 1050 microns in length. 
The medullary rays and wood parenchyma of the root re- 
semble in every way the corresponding tissues of the stem; but 
in the root the cells are uniformly larger. 
The phloém corresponds in structure to that of the stems 
(fig. 30, plate VI). However, there is a difference in the dis- 
tribution of the bast fibers. In the phloém of the root the 
fibers occur in larger groups than in the zone of parenchyma 
adjacent (fig. 30, plate VI), while in the stem the larger groups 
of fibers are found outside the phloém in the pericycle. In the 
thin-walled parenchyma cells throughout the bark there are 
large quantities of starch, and crystals of calcium oxalate. 
The cells have a yellowish-red color, and in all of them tannin 
is abundant. 
The elements composing the root xylem are the same as 
those found in the stem. The fiber tracheids, varying in 
length from 200 to 600 microns, are shorter and more irregular 
in form than are the stem tracheids (figs. 32, 33 and 34, plate 
VI). Frequently the root trahceids have blunt or irregularly 
shaped ends (fig. 32, plate VI). The most striking difference 
