Mr. Woops 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 4. 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. 
PaANICEE. 
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 palez 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. Spiculze 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. 
Spiculæ naked. 
B. Spiculæ not on such a rachis. 
0 
. Setaria. Spike compact, cylindrical. Spiculæ surrounded by an involu- 
crum of simple bristles ! ul 
4. Pennisetum. Spike compact, cylindrical. Interior bristles of the involu- 
crum feathery ! 
5. Panicum. Spiculæ in a scattered panicle, unarmed. Glumes and abortive 
paleæ of similar texture. 
