TAXONOMIC HISTORY OF THE DIOSCORE^ OF THE UNITED STATES. 9 



D. villosa Liun. 



D. quaieniata et quinata Gmel. 

 Obs. Cultura saepe fit glabra. 

 Hab. a Canada ad Cai'olinam. 



There is no reason why the name Dioscorea panicvlata should not 

 be adopted, for the description and range implicitly exclude the 

 dubious jjlant of Plukenet. 



The Vienna code provides for the rejection of names which are 

 likely to remain permanent sources of confusion and error. On this 

 ground the name Dioscorea villosa should surely be dropped. The 

 Linnanin diagnosis differs in only one word from that of Z>. saliva: 



6. Dioscorea [sativa] foliis cordatis alternis, caule laevi. 



7. Dioscorea [villosa] foliis cordatis alternis oppositisque, caule laevi. 



Moreover, the single character which Linnaeus used to distinguish 

 his Dioscorea villosa from his D. sativa (leaves, in the former species, 

 alternate a>id opposite) did not apply either to Plukenet's plant or to 

 that of Gronovius. The Gronovian specimen at the British Museum 

 has all the leaves alternate. The sheet bears this annotation : " Hinc 

 inde folia fert opposita, unde potius dicenda Dioscorea foliis cordatis 

 alternis oppositisve." Plukenet's plate shows no opposite leaves. As 

 Lamarck" pointed out in the passage ouoted below, the character 

 " foliis oppositis '' had a bibliographic origin with Plumier and Rum- 

 phius, whose Polygonatum scandens cdtissinium^ foliis Tainni and 

 Uhium niimmidarium are included by Linna?us in Dioscorea villosa^ 

 although he does not cite them. 



Je crois qu'une Iguame dont les feuilles sont les unes alternes & les autres 

 opposees, est un etre de raison ; que Linne a'a etabli son Dioscorea villosa que 

 sur les livres, eu voulant faire regarder conime la meme plaute le Bnjoniae 

 nigrae siinilis Floridana de Phikenet. le Polygonafum scandens alfissi)ni(m . . . 

 de Plumier, enfin VUbiiim nummiUarimn de Rumplie, qui sont trois plantes 

 tres-differentes eutr'elles. Mais la plante de Plukenet n'a aucuues feuilles op- 

 posees, constatees par I'observation ; au contraire, celle de Plumier, que j'ai 

 vue. & que je decris ci-dessous, n'a aucunes feuilles alternes. Quelle est done 

 cette Iguame de la Virginie & de la Floride, qui a en meme temps des feuilles 

 opposees & des feuilles alternes? Je n'en trouve aucun indice, soit daus les 

 livres, soit dans les Herbiers que j'ai pu visiter. Au reste, la figure citee de 

 Plukenet (t. 375, f. 5), ressemble beaucoup a la plante que Ton cultive au Jardiu 

 du Roi sous le nom de Dioseorea sativa, plante qui y subsiste eu plelne terre, 

 sans que la gelee fasse perir sa racine, ce qui me fait presumer que cette meme 

 plante n'est point des Indes, mais qu'elle est reellement originaire de la 

 Virginie. 



Wliile Linnaeus was writing the Species Plantarum, Burman was 



engaged in editing works of Rumphius * and of Plumier.'" An ap- 



° Encyclopedie Methodicpie P>otanique, iii (1789), p. 231. 



^Rumpbli Herbarium Amboinense (1741-1755). 



<^P]Mntarum Americanarum fasciculus (I, II . . . etc.), continens plautas 

 quas olim Carolus Plumierius detexit, eruitque atque in lusulis Antillis ipse 

 depiuxit (1757). 

 189 



