2 Mr. Woods on the Genera of European Grasses. 



In my younger days I never found myself at a loss to distinguish Arundo 

 from Avena on the one hand, or from Agrostis on the other, or Festuca from 

 Triticum ; yet I now observe that many species of Avena and of Agrostis have 

 hairs at the base of the florets, and that in Arundo they are not always long. 

 The hairs of Avena fatua, A. sterilu, &e. cover great part of the outer palea, 

 and are more rigid than in Arundo ; but the hairs in Arundo are not strictly 

 confined to the base, and Avena setacea has soft hairs rising from the base to 

 more than half the length of the palea. They are both absolutely and rela- 

 tively longer than iho^eoi Arundo {Deyeuxia) sylvatica. Avena has a jointed 

 awn twisted at the base; but this is also the case, though less obviously, in 

 some species of Arundo. Again, Aira is distinguished from Avena by having 

 only two flowers, but Avena subspicata, A. setacea, and some others have 

 hardly, if ever, more than two flowers. The characters of Avena and Bromus 

 in the English Flora seem to differ only in the adhesion of the seed in Bromus 

 to the inner valve alone of the corolla, while in Avena it is said to be united 

 to both valves. This peculiarity is not found in all the species of Avena, in 

 some of which the seed, though inclosed in the hardened paleee, is not united 

 to either. Yet Sir J. E. Smith is among the botanists who are most exact in 

 their descriptions, and most careful to make them contain some points of dif- 

 ference. That the outer palea is somewhat more rolled in at the edges, and 

 the inner somewhat more ovate, in Avena, are minute and comparative points 

 of difference, hardly sufficient for the foundation of a genus, even if they were 

 more constant than I find them to be. 



The manner in which a single species is transferred by different authors to 

 different genera shows that I am not singular in finding great difficulties in 

 this particular. Arundo tenella is an Agrostis with Roemer and Schultz. 

 Holcus, as separated from Sorghum, is united by De Candolle to Avena, while 

 Kunth places it among the Phalaridece. Bromus pinnatus of Linn, and of 

 Eng. Bot. became Festuca pinnata with later botanists, and the alteration was 

 afterwards adopted by Smith himself. Haller called it Triticum, in which he 

 is followed by De Candolle. P. de Beauvois formed for it a separate genus 

 under the name of Brachypodium, from the short stalks on which the spiculse 

 are placed. Mertens and Koch, after paring away many species from this 

 genus, still left in it B. pinnatus, and some other closely allied perennial 



