20 Mr. Woods on the Genera of European Grasses. 



are barren in some genera and perfect in others. The glumes are firm, nearly 

 equal, inclosing the paleae, which are thin, and often filmy, but bearing a 

 strong awn. The inflorescence is panicular, except in Andropogon, where 

 most of the species produce their spiculae in two rows on the same side of a 

 flattened rachis ; and the spikes or racemes thus formed are frequently dis- 

 posed in pairs or digitate. Flowers in determinate sets occur among the 

 Panicece, which, however, are easily distinguished by the coriaceous paleae. 

 They are also found in Hordeum, and in some foreign genera among the 

 Rottboelliaceoe. Elymus and Lygeum have two or three spiculse together, 

 but they offer nothing of a systematic arrangement. 

 The genera of this tribe -may be thus disposed : 



A. Spiculse all fertile, clothed with long silky hairs. Glumes thin. 



1. Saccharum. Palese unarmed, the inner small or wanting. Squamulse 2. 



Panicle not spike-like. 



2. Imperata. Paleae 2, unarmed. Squamulse none. Panicle spike-like. Rachis 



abruptly flexuose, continuous. 



3. Erianthus. Outer palea awned. Squamulae 2. Panicle spreading. Rachis 



hardly flexuose, very brittle. 



B. Lateral or stalked spiculse barren. 



4. Andropogon. Spiculse linear-lanceolate, compressed. Seeds nearly linear. 



5. Sorghum. Spiculse ovate or ovato-lanceolate, turgid. Glumes of the fer- 



tile floret coriaceous or horny. Seed roundish. 



The second and third genera were struck off* from Saccharum by Palisot de 

 Beauvois. The true Saccharum has, as it appears from this author, only one 

 palea and no awn or seta. 



Imperata and Erianthus differ, as stated above ; but these distinctions are 

 not sufficient to constitute genera unless supported by a marked peculiarity of 

 habit ; and where we have only one species of a genus, as in Imperata, we can 

 hardly acknowledge some difference of general appearance to decide the 

 question, since we have no proof of its having any connection with the cha- 

 racter. I may add to the foregoing description of Imperata, that in all my 

 specimens the styles are united in the lower part. The very tough and horny 



