THE DEUG DIOSCOKEA. 



23 



the rhizoma resembles that of the true wild yam, while the lower portion is in 

 like manner covered with stout fibrous rootlets. The color is generally a very 

 much darker brown. 



It will be observed that Mr. Lloyd's " true " Avild yam is Dioscorea 

 paniculata and that his " false " variety is D. glcvuca^ the species 

 first authoritatively introduced into eclectic practice. With regard to 

 his criterion for distinguishing "Z>. villosa " from "Z>. villosa var. 





Fig. 6. — Rhizomes of Dioscorea paniculata from Agricultural College, Ingham Co., Mich., 

 collected by W. .1. Deal. (Two-thirds natural size.) 



glahra " (the pubescence of the lower leaf face), it must be said that 

 D. glauca^ the plant Avith the large, coarse rhizome, although some- 

 times glabrous, is oftener somewhat pubescent on the leaves beneath, 

 and that D. paniculata^ the species with slender rhizomes, has 

 a variety with the leaves entirely glabrous. To make this point 

 clear, the attention of the reader is directed to figure 5, which illus- 

 trates the rhizome of a specimen of D. glauca with the leaves slightly 



189 



