ioi6] SIIERFF—BIDENS 503 



mature achenes match the ovary figured by Kunth and show that 

 there is not the slightest tendency to become rostrate as in Cosmos. 



An examination of the original description of Bidcns parvulifolia 

 (Sherff , loc. cit.) shows that the second cited specimen (which I had 

 seen in the U.S. Nat. Herb.) was obtained by the same collectors at 

 the same altitude, time, and locality as was Hcyde and Lux 6173 (see 

 foregoing) . The dried ligules were yellowish, the leaves were pubes- 

 cent, and all but the top pair were simple. Since then, however, 

 I have found other specimens (Heyde and Lux 0102 and 6163) show- 

 ing numerous intergradations between the simple, pubescent leaves 

 and the compound, mainly glabrous leaves; also, variations to a 

 roseate color are shown in the rays. Thus Bidcns parvulifolia, 

 incredible as it will seem to any botanist who does not have at hand 

 the intermediate specimens, must be interpreted as merely a form 

 of Bidcns chrysanthemifolia having minute, mainly undivided leaves. 



Bidens cernua L. Sp. Plant. 832. 17 53.'— Bidcns gracilenta 

 Greene, Pi ttonia 4:255. 1901; Bidcns prionophylla Greene, loc. cit. 

 256; Bidcns glaucescens Greene, loc. cit. 258; Bidcns lonchophylla 

 Greene, loc. cit. 258; Bidcns Macounii Greene, loc. cit. 259; Bidcns 

 leptopoda Greene, loc. cit. 260; Bidcns marginala Greene, loc. cit. 262. 



In 1901, Greene (loc. cit.) described a number of new species of 

 Bidcns. On examination of his types (mostly in U.S. Nat. Herb.) 

 and cotypes (mostly in Herb. Gray and in Herb. Field Mus.) 

 nearly three years ago, I was dismayed to find that most of these 

 species represented what ordinarily had been regarded as mere 

 ecological forms of Bidens cernua and B. lacvis. Direct conversa- 

 tion with Dr. Greene himself showed that back of his viewpoint 

 regarding B. cernua (Greene loc. cit. 251-253) was the absolute con- 

 viction that the American specimens were native to America, and, 

 being so, were hence specifically different from European specimens. 8 

 However, personal field study for the past four autumns, combined 



7 Here, as elsewhere in this series of articles, only the most relevant synonyms are 

 cited, the others being left for a complete monographic treatment later. 



8 In emphasizing his views upon this subject, Dr. Greene exclaimed: "I defy 

 you to find a single species of Compositae that is native both to Europe and to North 

 America." It is not my intention to discuss this opinion here, since it is quoted merely 

 to show his viewpoint. I do desire, however, to acknowledge with gratitude the 

 courtesies shown me by Dr. Greene from time to time. For over two years we had 

 been making field observations for each other upon various species of Bidcns, but his 



■ recent death brought this mutual aid to an abrupt end. 



