ORCHIDACE.E 



to offer important differentiating characters, although these are 

 more or less relative in value and consequently of questionable 

 vi^orth in a systematic arrangement of species in such a puzzling 

 group as the Physurese. In both the SpiranthccE and Physureae 

 the dangers to a stable system of classification from excessive 

 segregation of genera are very great. Even the most careful 

 disposition of species in genera may be severely disturbed by 

 morphological exceptions. Whether or not convenience is sub- 

 served by the multiplication of genera in such groups as the 

 Spirantheae and Physurese, it is often quite evident that affinities 

 are frequently neglected. 



[81 ] 



