PREFACE 



IN the present volume of Orchidaceae I have brought together 

 several short papers which represent studies of genera and 

 species taken from a wide geographical range. 



The paper on Pogonia and its Allies in the Northeastern 

 United States may annoy those who are weary of the nomen- 

 clatorial instability which seems more and more inseparable from 

 systematic botany ; in fact, this paper may appear to be an at- 

 tempt to justify a modern tendency that is positively dangerous 

 in the realm of taxonomy. I have endeavored to show by plates 

 of commendable completeness every structural character that 

 seems important in the contemplation of generic cleavage. If 

 these characters do not carry conviction, the plates that display 

 them will, at least, furnish to opponents of change an accurate 

 record on which to base objections and from which to draw 

 conclusions. 



The paper on Otostylis and Cyrtopodium does more than 

 clarify a perplexing situation: it trenchantly reveals a difficulty 

 that is always present when we attempt to identify plants. It 

 indicates that many of our most carefully approached determi- 

 nations may be faulty even when contrasted characters fit to- 

 gether with delightful ease. 



Oakes Ames 



Bussey Institution for Applied Biology 

 Harvard University 



January, 1922 



