IRbobora 



JOURNAL OF 



THE NEW ENGLAND BOTANICAL CLUB 



Vol. 8. May, 1906. No. 89. 



NOTES ON trisp:tum and graphephorum. 



F. Lamson-Scribner. 



The limitations of the larger genera of the tribe Aveneae are in 

 no case clearly defined, and the classification of many of the species 

 will always be determined with more or less doubt, resting finally upon 

 the judgment of the agrostologist, rather than upon any definite char- 

 acters. Some of the smaller genera in the tribe are established upon 

 purely technical or artificial characters subject to more or less individual 

 variation, and at best of (jucstionable taxonomic value. Such are 

 Aira, Graphephorum, and Venienaia, while one has only to consult the 

 synonymy of the species of Arena, Deschamp.s'ia and Trisetum to dis- 

 cover how varied have been the views concerning them, species resting 

 for a time in one genus only to be shifted by a later author to another, 

 until some have figured for a season in three or even more recognized 

 genera. Botanists have repeatedly attempted to fix upon characters 

 which would sharply outline a genus, and in some cases have sought to 

 attain this result by establishing new genera. Deschampsia, Dan- 

 thonia and Trisetum were thus segregated from Aira and Avena, but 

 with the advancement of our knowledge through the investigation of 

 more abundant material and discovery of "new" species, the generic 

 limits have been broken here and there until we are forced to admit the 

 futility of the attempt, accepting the fact that the different groups or 

 divisions of organic life even to the ultimate specific units, however 

 natural they may appear, present variations which, in one way or 

 another, so connect them together that they present a unity of develop- 

 ment wherein genera and species become simply the expressions of the 

 scientist, merely serving to facilitate his efforts in studying the grand 

 scheme of nature. 



