262 KANSAS UNIVERSITY SCIENCE BULLETIN. 



The epidermis of the stem is closely covered with hairs, 

 which are of the same general type as those of the leaf (figs. 

 4 and 8) . The hairs are mostly stellate, with from five to nine 

 rays. Each ray is a single cell, the center of which stains 

 darker with safranin than the outside, giving the appearance 

 of a core. There are also many simple unicellular hairs, simi- 

 lar in structure to one ray of the stellate hair, and many 

 glandular hairs, knoblike in shape (fig. 8, /). These latter are 

 frequent on the young parts of the stem and petiole and large 

 veins of the leaf. The epidermal cells of the stem (fig. 7) are 

 rather irregular in size and shape but have a general rec- 

 tangular form. The stomata (fig. 7, a) vary more in shape than 

 those of the leaf and are slightly larger. They stand with the 

 long axis parallel with the long axis of the stem and are not 

 so close together as those of the leaf. 



Collenchyma is always present in young stems (figs. 25-26, b 

 and 30-33, a) and in the petioles of the leaves (fig. 22, c), but 

 in older parts of the stem it is thrown off when cork (figs. 

 34 and 35, a) is formed. 



The vascular bundles are of the usual collateral type, and the 

 bast fibers stand just outside of the phloem strands, making a 

 broken line around the outside of the phloem (figs. 32, 33 and 

 38) . The vascular bundles vary in size, and a large and a small 

 one or two large ones and two or three small ones are often 

 found alternating. The cross section of the very young stem 

 is irregular in shape instead of being circular as in the older 

 parts of the stem, and the large bundles are likely to be where 

 the stem is prominent (fig. 30). In the older part the stem is 

 nearly circular and there is less irregularity in the size of the 

 bundles (figs. 30-35). 



The changes in structure from the new to .the older parts of 

 the stem are shown in figures 30-35. The sections from which 

 the illustrations were made were taken from the stem, first 

 just below the growing point, second about two inches below, 

 and at intervals all of the way down the stem to the root, 

 representing six different regions of the stem. In the first 

 four sections the pith covers the greater part of the diameter, 

 but in sections nearer the base of the stem the pith becomes 

 smaller and is nearly crowded out of existence. 



The bast fibers are found in sections about three inches from 

 the apex of the stem, a bundle of bast fibers standing before 



