﻿The Mycorhizae of Aplectrum. 



D. T. MacDougal. 



* 



In April, 1876, Mr. H. Gilman collected a specimen of Aplec- 

 irum spicatum near Detroit, Mich., which he described in the Bul- 

 letin of the Torrey Botanical Club, 6:94. 1876, as being 

 furnished with coralloid roots, and as parasitic on the roots of 

 trees. The specimens was sent to Dr. Gray, who informed 



M 



Gilman that such formations were "indeed unexpected/' and the 

 matter rested. 



I have recently rediscovered this formation on a clump of 

 plants near Lake Minnetonka, and my preliminary examination 

 reveals much of interest concerning this variation in form, as well 



as some important facts concerning the general biology of the 

 typical plant. 



Aplt 



May 



ing in August persistent throughout the winter. The corm gives 

 off one or two lateral offshoots, upon the ends of which daughter 

 corms arise, repeating the history of the parent corm. 



The plant lives in humus, and it appears that it must be con- 

 sidered a hemi-saprophyte, both from anatomical and experimental 

 evidence, although work upon this point is not complete. 



The short straight unbranched roots are from ten to sixteen in 

 number, and arise from the lower part of the corm. These organs 

 entertain two fungi in such manner as to form an ectotropic and an 

 endotropic mycorhiza. The endotropic fungus forms masses of 

 hyphae nearly filling the greater number of the cortical cells of 

 the root, and sending single filaments out through the root hairs 

 into the humus soil. The nuclei of the cortical cells containing 

 the fungus are very large and hyperchromatic, and it is evident 

 that the fungus is beneficial to the tissue inhabited by it. Its gen- 



*Preliminary notice read before the Indiana Academy of Science, December 30, 



1897. 



(110) 



