126 ME. G. BENTHAM ON GBAMINEiB. 



65. Gltcebia, Br., if we include Atropis, Eupr., is a genus of 

 nearly thirty species spread over the extratropical region?, northern 

 or southern, both of the New and the Old World. It is very 

 nearly allied both to Poa and Festuca, differing from the former 

 in the flowering glumes rounded at the base without any promi- 

 nent keel, from Festuca in the broader more obtuse glumes, and 

 the grain usually free from the palea, and from both in the short- 

 ness of the nerves of the glumes. The habit is somewhat variable, 

 but as much so in each section as in the whole genus. The two 

 sections into which it has been divided, often raised to the rank 

 of separate genera, are : — 1. Hy&rochloa, Hartm. (Forroteranihe, 

 Steud., Exydra, Endl., Olyceria proper of many botanists), with 

 the lodicules connate and truncate or deficient, and the thick grain 

 only marked on the inner face with a very narrow lined furrow or 

 quite smooth ; and 2. Atropis, Eupr. {Fuocinellia, Parlat.), with 

 two distinct lodicules and the grain more or less compressed from 

 front, to back, with a broad furrow or almost fiat on the inner 

 face. But these characters are not constant. The lodicules in 

 the typical SydrocMoa, Q. fluitans, Br., though thicker than in 

 Atropis, and usually connate, are readily separable and occasion- 

 ally spontaneously free ; in Q. aquatica, Sm., they are so short as 

 to render it diiBcult to say whether they do or do not cohere, and 

 in Q. nervata, Trin., and in Q. pallida, Trin., I can find no trace 

 of them ; in Atropis they are usually, but not always, more deve- 

 loped and thinner. The shape of the seed and of its furrow seems 

 to vary from species to species, in so far as I have been able to 

 procure it well ripened. 



66. Eestuca, Lian., is one of the genera as to whose limits 

 botanists are the least agreed. "With the exception of the exclu- 

 sion of Cutanda and Frizopyrum, we have followed generally the 

 arrangement proposed by Cosson and Durieu, which would include 

 between seventy and eighty species (estimated by some at above 

 two hundred and thirty), almost cosmopolitan in their geogra- 

 phical distribution, but most abundant in the northern temperate 

 regions of the Old World, with not many American and very few 

 tropical species. They are generally distinguished in the sub- 

 tribe by the flowering glumes rounded without any prominent 

 keel at least at the base, and acute or awned at the end, and by 

 the glabrous grain adhering to the palea. But there are excep- 

 tions to each of these characters ; and some species run very much 

 into Foa, whilst others are scarcely distinct from Fromus. The 



