XXX 



38. Phragmites. — Flowers awnless, with siliy hairs at the base ; 

 lower one of each spikelet imperfect. 



***** Inflorescence of two or more unilateral spikes on the same 



culm. 



47. Spartina. — Spikes two or three, erect. Spikelets single- 



flowered, in two rows. Style divided above. 

 Stigmas elongated. 



48. Cynodon. — Spikes spreading, digitate. Spikelets sessile, 



in a single row. Styles two. Stigmas short. 



49. Digitaria. — Spikes spreading. Spikelets pedicellated in 



pairs. Styles two. Stigmas short. 



The above definitions must' not be regarded as having other than mere 

 general application, but, conjoined to a careful comparison of specimens 

 with the more extended generic characters as given in the text and 

 corresponding figures, will be found useful. 



Since the publication of the earlier numbers of this monograph, my 

 remark, that Anthoxanthum is the only native grass the flowers of 

 which are constantly diandroiis, has been a subject of private comment 

 on the part of some of our botanical subscribers, who consider it 

 erroneous, directing especial attention to Broraus diandrus and 

 Hierochloe lorealis. In the first of these, a third stamen is, perhaps, 

 more frequently present than the contrary ; while the only wild speci- 

 men of the latter that ever came under my examination, had several 

 of the central flowers of the spikelets, in this respect, corresponding 

 to the lateral ones ; and in garden examples the triandrous structure 

 is almost as frequent as the diandrous. Such is not the case with the 

 flowers of Anthoxcmthum. The botanical student may learn from 

 these facts not to over-value characters the permanence of which 

 alone can confer upon them any real significance, a principle that it 

 has been sought to illustrate, on the broad scale, throughout the 

 volume now laid before him. 



