84 



color and surfaces of the leaves, and size and form of the fruits. 

 Some of the new species are separable in the seedling stage when 

 three or four leaves have been formed, the rosette presenting a 

 characteristic picture. De Vries suggests that the mutants or 

 species derived by mutations in his experiments are quite as 

 clearly separable as the species recognized in the currently ac- 

 cepted classifications of the oaks, hieraciums, or cochlearias. 



( To be continued. ) 



OUR YELLOW LADY'S-SLIPPERS 

 By P. A. Rydberg 



Some time ago I received a letter from Mr. Oakes Ames, of 

 North Easton, Mass., which contained, among other matters, the 

 following lines : " While looking over your revision of the Or- 

 chidaceae in Dr. Britton's ' Flora of the Northern States and 

 Canada' (1901), I noticed that your key for the genus Cypri- 

 pedium gives as a characteristic of C. pubescens {liirsiitiwi) a pale 

 yellow lip, flattened vertically, and as a characteristic of Cypri- 

 pedium parviflorum, a bright yellow lip, flattened laterally. Have 

 you found in working up your material that the case is reversed 

 after all, and that Hooker, Gray and others were confused in 

 their ideas ? " 



Although I revised the manuscript of the Orchidaceae for Dr. 

 Britton's Manual, I did not find anything in the treatment of 

 Cypripcdium that I thought needed a change, but left that genus 

 practically as Dr. Britton had it in the " Illustrated Flora." I 

 added in this case the differences in the flattening of the lip, 

 which character had been used here at the Garden. My under- 

 standing of the two species was, however, the same as that of 

 Dr. Britton and I had no idea that Hooker, Gray or others had 

 any other understanding. I thought, therefore, that the differ- 

 ence between the characteristics given by them and by us was 

 more apparent than real and that it depended upon a different 

 interpretation of terms. I, therefore, wrote to Mr. Ames, ex- 

 plaining my use of the words "vertically" and "laterally" flat- 

 tened. By vertically flattened, I mean such a flattening as 

 would be produced by a pressure from above and below, the 



