Holm, Some iiew anatomical characters for certain Gramiueae. 133 



number of Hydrophytes to which so-called xerophilous structures 

 are common. 



Comparing the structure of the Gramineac, which we have 

 disciissed in the preceding pages, it does not seem that Aristida 

 from the plains of Colorado has characteristics warranting the 

 designation of the species as a xerophyte in contrast to ^.1. spici- 

 formis and palustris from pine-barren ponds in Florida, which 

 latter from their habitat would he called Hydrophytes. Similarly 

 the species of Sporobolus are in no wise to be separated on 

 structural grounds into Xerophytes or Halophytes. It seems, in othcr 

 words, very unsafe to conclnde that the inhabitants of deserts, 

 bogs etc. exhibit a corresponding structure which should be com- 

 mon to all plants from similar surroundings. On the other band 

 we may well speak of bog-plants, desert-plants etc. these terms 

 being only applicable as far as concerns the nature of the 

 surroundings, but not including the internal structure. We have, 

 therefore, raade no attempt to classify the species of Aristida, 

 described above, as Xerophytes or Halophytes, inasmuch as avc 

 have not examined more than about half of the species known of 

 this genus. 



We simply desired to call attention to the structural peculia- 

 rity exhibited by some of the species, which may prove of some 

 advantage to a future Classification of these, besides that the 

 sketch of the leaf may furnish some illustration of the general 

 structure of the Gramineae from the plains and prairies of North 

 America. 



Brookland, DC, Febry. 1901. 



Bd. XJ. Beiheft 2. Bot. Centralbl. 1901. 



