Mr. Woods on the Genera of European Grasses. 21 



glumes and large swelling seeds of Sorghum appear to me to separate it suf- 

 ficiently from Andropogon, and the habit is very different. Yet Kunth unites 

 them, and Brown seems to rest their distinction exclusively on the inflores- 

 cence, which in Andropogon is usually in one-sided spikes, often in pairs or 

 digitate, while Sorghum has an equal, diffuse panicle. I must confess that 

 the glumes of A. Allionii and of A. Gryllus are, when in seed, nearly as hard 

 as in Sorghum, though not so thick and solid, but the glumes of Sorghum are 

 hard even while the plant is in flower. 



Panicky. 



These have two glumes, one of which is generally much smaller than the 

 other, and sometimes reduced to a hardly distinguishable rudiment. Within 

 these we find what appears in the European genera to be a third glume, but 

 which analogy teaches us to consider as the rudiment of a barren exterior 

 floret. In Oplismenus we may sometimes observe within this rudiment a filmy 

 palea ; and, in several tropical species of the tribe, this part is furnished with 

 anthers. This barren floret seems to do the duty of a glume in the protection 

 it affords to the fertile one. The palese of the latter are very firm and coria- 

 ceous or horny. They are dotted, or quite smooth, rounded or almost flat- 

 tened at the back, without midrib or prominent nerve ; but nerves are in some 

 species distinguishable in colour, especially towards the apex of the palea. 

 The European genera are as follows : 



A. Spiculae in two rows on one side of a flattened rachis. 



1. Digitaria. Spikes fingered, unarmed. 



2. Oplismenus. Spike compound ; one-sided in the whole and in each part. 



Spiculse naked. 



B. Spiculee not on such a rachis. 



3. Setaria. Spike compact, cylindrical. Spiculse surrounded by an involu- 



crum of simple bristles ! 



4. Pennisetum. Spike compact, cylindrical. Interior bristles of the involu- 



crum feathery ! 



5. Panicum. Spiculse in a scattered panicle, unarmed. Glumes and abortive 



palese of similar texture. 



