No. 539] ORIGIN OF SPECIES IN NATURE 663 



cence. In fact, there are leaves which possess a midrib 

 only. 



What appears to have been the same plant has been 

 described in a recent publication, 53 as occurring in two 

 different places about Joliet, 111., and near Champaign, 

 111. Here the inflorescence is referred to as " irregular 

 with numerous small sterile flowers. " It is also reported 

 from South Bend, Ind. 54 Previously its appearance had 

 been noted near Jessup, Ind. 55 Here also the inflores- 

 cence is described as "irregular, heads numerous, mostly 

 small, rudimentary and apparently sterile." From an 

 article by Fernald and Wiegand 56 it is gathered that 

 Darlington in his "Flora Cestrica" referred to a 

 similar plant. 57 



To Professor Fernald, who saw Darlington's speci- 

 men in the Gray Herbarium, I am indebted for the fol- 

 lowing: 1 'Darlington's sheet bears the note: var. foliis 

 pinnatifidis vel potius grosse dentatus. "West Chester, 

 Pa., August 25, 1858. These are imperfect specimens of 

 the plant referred to in Fl. Cestrica, p. 156 ; but I am not 

 sure that it is the one spoken of in Gray's Manual. The 

 inflorescence always has a kind of half-starved or semi- 

 abortive appearance. W. D." 



The general appearance of the inflorescence certainly 

 suggests a teratological development, giving an impres- 

 sion similar to that caused by inflorescences of Rhus 

 glabra infested with a certain gall. But an examination 

 of the living plants, at least such was the case with those 

 at Albion, at once does away with any question as to 

 their normal condition. The peculiar ragged appear- 

 ance of the flowering shoots is merely due to a progres- 



