266 KANSAS UNIVERSITY SCIENCE BULLETIN. 



lage tube or pocket. Kuntze says that it is generally the inner 

 wall of the epidermis that swells most in water. This is true 

 of Malva rotundifolia to some extent, but it is not always the. 

 case. It is stated as a characteristic of Malvacex that the epi- 

 dermis of the leaves strongly swell in water, in some species 

 all of the cells and in others only certain cells, and these some- 

 times in the upper epidermis only. In M. rotundifolia the 

 mucilage is only in certain cells of the epidermis, and there is 

 much more in the upper than in the lower. 



Stomata are found on both sides of the leaf (fig. 18) in 

 about the same numbers. They are more numerous in the 

 fully developed leaf than in the young leaf. The average num- 

 ber to the square millimeter of the fully developed leaf is 

 about 494, and of the young leaf 370. The stomata are in the 

 same plane with the other epidermal cells or but very slightly 

 project (fig. 10, c and d) . There are extensive air spaces be- 

 neath the stomata, and the spaces in the spongy parenchyma 

 communicate freely with them. Chloroplasts seem to be less 

 numerous in the palisade cells than in the spongy parenchyma. 



The veins are embedded in the spongy parenchyma, and only 

 the main veins reach out to the epidermis. All veins are sur- 

 rounded by large very thin-walled border parenchyma (fig. 14) 

 whose cells have their long axis parallel with the length of the 

 veins. The veins end free in a group of tracheids (figs. 1, 2, 3 

 and 11, h) . Near the margin where the large veins terminate 

 these groups are very complex (fig. 1, a, and 3). In each lobe 

 of the leaf the central rib gives off lateral veins almost at right 

 angles, in fact all of the angles in the branches of veins ap- 

 proach nearly a right angle. The veins are well distributed, 

 making a close network throughout, with the ultimate branches 

 standing about .09 millimeter apart in the old or fully devel- 

 oped leaf, and .11 millimeter in the young leaf. 



ROOT. 

 The root is a tap-root going down more than two feet into 

 the ground. There are but few lateral roots and no large ones. 

 The bark of the root is very thick, covering about two-thirds 

 of the diameter. Cork is formed on the outside as on the 

 lower parts of the stem. The root contains a great amount of 

 food material stored in form of starch, sugar, mucilage and 

 protein. During the growing season there is only a trace of 

 mucilage in the root, and not as much starch and sugar as in 



