32 Mr. Woods on the Genera of European Grasses. 



PiPTATHERUM IS a gcnus of 4 or perhaps 5 species, all European, which were 

 separated by Palisot de Beauvois from Agrostis and Milium. Kunth says of the 

 spiculee of Piptatherum, " basi baud articulatse." I am ignorant of the precise 

 import of this phrase. None of the Stipacece are described as having the spi- 

 culee articulate at the base. Such a character might well be given to a plant, 

 for instance, like Imperata cylindrica, where the whole spicula, glumes in- 

 cluded, readily separates from the callus which supports it. In Melica also 

 the calyx appears to fall off; but in most Grasses the separation of the floret 

 takes place within the glumes, and this seems to be the case with all the 

 Stipacece. In S. aristella the floret is sessile, and the awn neither geniculate 

 nor twisted ; perhaps it ought to form a distinct genus, or be united to Pipta- 

 therum. In the Mantissa it is called an Agrostis. In all the other species the 

 awn is geniculate and generally with two knees, which, however, are not very 

 acutely bent. The part between the knees is less closely twisted than the 

 lower part of the awn, but in the same direction. Two broad ribs run down 

 the awn, and each side of each rib is furnished with a row of hairs, which in 

 some species are short and bristle-like, in others soft and long, or bristly in 

 the twisted part, and longer and finer in that which is not twisted. Duby in 

 the Bot. Gall, describes S. capillata " aristis basi rectis apice tortilibus ;" but 

 this is certainly erroneous. I have preferred the name of Achnatherum given 

 by Palisot de Beauvois to the inadmissible compound Lasiagrostis adopted 

 from Link by Kunth. It is true that some species were included by the first- 

 mentioned writer, which succeeding botanists do not acknowledge ; but as 

 these are sunk in other genera, they form no objection to the appropriation of 

 the name to this. In habit the European, and probably the Siberian species 



approach to Arundo. 



Arundinace^. 



This tribe, like the following, contains some plants of which the spiculse are 

 one-flowered, and others in which they are many-flowered, but with so much 

 similarity of habit and structure, that Linnaeus united them all into one genus. 

 I follow other botanists in finding the technical difference in the long silky 

 hairs which envelope the florets, but I confess it to be a nice point to di- 

 stinguish the tribe on this ground. Some species of Agrostis, as has been 

 already observed, are not entirely destitute of such hairs, and nearly if not 



