Monotropaceae with Reference to Ericaceae 



69 



In M. uniflora the epidermal cells are similar to those of 

 M. hypopitys. The transverse type of stoma is much more 

 frequent, the longitudinal type being rather rare. Fig. 4, 6-10 

 shows a series in the formation of a transverse stoma from the 

 longitudinal. 6 is a normal stoma. In the growth of the stalk 

 the guard cells gradually become pulled apart and slightly 

 turned around as in 7. In 8 the slit is diagonal, 9 shows 

 the cells almost completely around, and finally 10 shows the 

 directly transverse slit. 



Portions of the epidermis of boiled-up material of Pleuri- 

 cospora were found to have shorter thicker walled cells than the 

 preceding. No hairs or stoma ta have as yet been seen but the 

 material at hand was limited, so this does not finally preclude 

 the possibility of their occurrence. Hairs similar to those found 

 on the axis in Pyrolaceae and Monotropaceae are characteristic 

 of many of the Ericaceae. This is another close similarity 

 found in the three families. 



Fig. 5. Transverse section of ascending axis, showing sector of fibrovas- 

 cular system X 200. 



1. Chimaphila umbellata 



2. Pleuricospora fimbriolata 



X = xylem; P = phloem; HB = hard bast; C = cortex. 



Transverse sections of the ascending axis were taken at a 

 point half way between the flower or flowers and the leaves, 

 or in the Monotropaceae half way between the flowers and the 

 base of the ascending axis. 



In C. umbellata the epidermis appears as a hollow cylinder of 

 oval cells with a thick outer cuticle and covering of wax. The 



