MYCORHIZAS 



247 



Note the degeneration of the shoot of Monotropa as a result of 

 its altered nutritive relations (Fig. I25). 1 



Secure clumps of any species of Corallorhiza and wash away the 

 soil. The coralloid underground organs are found to show inter- 



FIG. 124. Longitudinal section of apical portion of mycorhiza of Corallorrhiza Ari- 

 zonica. a, a, epidermis, m, M, mycelial layer of fungus, b, b, cortical region of- 

 branch in which organs of interchange of the fungus are formed, c , stele. J, d, d y 

 secondary branches. ^, scale-leaf at apex of branch. 



nodes, and hence are stems, the roots having been lost as a result of 

 the mycorhizal adaptation. Cut cross and longitudinal sections of 

 some of the smaller branches. Note the tubular extensions of 



B c 



FIG. 125. Monotropa uniflora. A y longitudinal section of stele of root showing 

 vessels and contiguous phloem cells. B, transverse sections through mature and 

 young roots showing vessels. C, mass of roots from which arises a flowering shoot. 



1 MacDougal and Lloyd. The roots and mycorhizas of some of the Monotropaceae. 

 Bull. N. Y. Bot. Garden. I : No. 5. 419. 1900. 



