MISSISSIPPI EXPERIMENT STATION. 35 



textxire as kohlrabi lea\'es; they, like the leaves of kohlrabi, when bent, 

 tend to remain so (like a bar of lead) ; that is, they seem to lack power of 

 springing back into normal shape. 



The thickening of the stem is not so large as in kohlrabi, but, 

 except being nearer the ground, is much like it. The radish stem has 

 no thickening of this sort. The root is about the same size and shape 

 as the radish root, but is much more branched. It contains a thicker 

 cortex and a woody central part. The root of kohlrabi is small, 

 woody and much branched. Xo young plants have been seen rising 

 from the roots of either parent. 



Cabbage worms ate the hybrid greedily, it being a task to keep 

 them off; they ate kohlrabi to some extent, but did not eat the radish at 

 all. The hybrid had a taste somewhat different from that of either 

 parent, a decided turnip taste in addition to the pungent taste of the 

 radish parent. 



Raphanus salivas, Bassica olcracea, var. caulo-rapa and Hybrid. 



HISTOLOGICAL CHARACTERS. 



Stem Structure: The Radish stem, as was stated above, has 

 no enlargement corresponding to the stem thickening of Kohlrabi 

 and the hybrid. The stem in this part of the plant is from 1.5 to 2 cm. 

 thick. A cross-section shows a fairly well defined cortex, within which 

 is a woody ring 3-4 mm. in thickness, and in the center, there is a mass 

 of spongy pith (fig. 38 b.). A cross-section of the corresponding part 

 of Kohlrabi, shows a comparatively narrow but well defined cortex 

 within which is a ring of small, irregular, scattered vascular bundles, 

 while the central part, forming the main mass of the structure, consists 

 of more or less succulent parenchyma tissue in which there are a few 

 small, scattered vascular bundles (fig. 37 b.). The hybrid stem at this 

 point has a rather thick cortex, which varies in thickness in different 

 places; within this is a woody ring, consisting of wide, flat plates of 

 Xylem of varying widths, and rather loosely joined. The central part 

 of the structure is here also made up of rather succulent parenchyma 

 tissue, being similar to the tissue of the corresponding part of Kohlrabi, 

 but even more dense. 



Taking up stem structure in more detail, we notice that each of 

 the three plants under comparison has a well defined epidermis, the 

 cells being flattened somewhat. In Radish they are 21 - 24m thick, 

 and 33 - 68m long; in Kohlrabi, 15m thick, and 15 - 45m long; and in the 

 hybrid, 15 - 21m thick, and 20 - 30m long. Over certain parts of the hybrid 

 stem, the epidermis has disappeared, and these parts are covered by a 

 periderm consisting of several layers of cells which are more or less 

 suberized. 



The cortical cells of the three plants are similar in form and texture. 

 In Radish and the hybrid, they gradually shade off into the ground tis- 

 sue of the central part of the stem, but in Kohlrabi the cortex is limited 

 inward by a more or less well defined cambium. 



The prominent woody ring of the Radish stem is made up of xylem 

 strands that fit together rather closely. These strands are grouped in a 

 peculiar manner, 3 to 5 or 6 nm together toward the pith and in the form 



