SYNOPSIS OF THE SPECIES OF DIOSCOKEA. 11 



he had written a full description. He recognized two species, which 

 he treated as follows: 



Dioscorea : (1) villosa 2/ bairy Pens. fl. Jim. Virg; (2) glauca 1/ glaucous 

 Peus. tl. Jun. 



Only two species have been found in a large series of specimens 

 from Pennsylvania. One of them, Dioscorea paniculata, corresponds 

 to the D. villosa of Muhlenberg, and the other must therefore be 

 called D. gJauca. There is nothing to represent Muhlenberg's name 

 in his herbarium at the Philadelphia Academy of Natural Sciences, 

 but there can not be the least doubt that it has been applied to the 

 correct plant. 



Rafinesque " described four Dioscoreae in 1830. Two of them 

 D. megaptera and D. hexaphylla may be referred to D. glauca, and 

 one, D. repanda, may be divided between D. glaiica and D. quater- 

 nata. The other, D. longifolia^ described from leaves only, it is im- 

 possible to identify. 



In 1850 Kuntli '' jDublished Dioscorea pruiiiosa. No specimen is 

 preserved at Berlin. From his full description, however, it seems 

 clear that the plant should be referred to D. glauca. 



Between the years 1850 and 1909 all of our Dioscoreae were treated 

 in botanical works as one species under the name Dioscorea villosa. 

 In the seventh edition of Gray's Manual (1909) the editors departed 

 from current usage in taking up D. villosa var. glabra^ a name ob- 

 scurely published by Mr. C. G. Lloyd in 1880,"" and afterwards used 

 in various medical works.*^ Careful study of all the evidence available 

 has shown that this name is likewise a synonym of Dioscorea glauca. 

 Mr. Lloyd's very valuable observations on the medicinal rhizomes of 

 the two plants distinguished by him as D. villosa and D. villosa var. 

 glabra will be given due attention in another connection. 



SYNOPSIS OF THE SPECIES OF DIOSCOREA. 



Staminate inflorescences solitary and occurring only in the leaf axils. 

 Lower leaves verticillate in 4"s to 7's. 



Leaf blades green below when mature, usually glabrous, 



1. D. quatemata. 

 Leaf blades glaucous below when mature, generally hirtellous, 



2. D. glauca. 



"New Flora of North America, second part, Neophyton (1836), pp. 88-89. 



^Enumeratio Plantaruni, v. (1850). p. 330. 



'^ King, John, and Lloyd, John Uri, Supplement to the American Dispensatory 

 (1880), pp. 81-83. 



^ Several editions of King's American Dispensatory, revised by H. W. Felter 

 and J. U. Lloyd. 



A Treatise on Dioscorea and Sulphurous Acid. Drug Treatise No. 14, issued 

 by Lloyd Brothers (1905). 

 189 



