32 ilE. a. BENTHAM ON SEAMINBiE. 



the lowest glume, leaving, as the spikelet falls away, a slight 

 dilatation or callosity at the apex of the persistent portion. 

 Sometimes it is not easily observed at the time of flowering, hut 

 becomes more marked as the fruit ripens. A similar marked 

 articulation has not hitherto been observed in PoaceiB, except in 

 FingerhutUa. There are also a very few cases where the lowest 

 glumes are reduced to slight callosities, or are so rudimentary as 

 to render it difficult to say whether the articulation is in the 

 pedicel or in the rhachilla. In the Getichrus group of the tribe 

 Panicese, in the subtribe AnthephoresB of Zoysieae, and in some 

 AndropogonesB, the articulation is not under each spikelet, but 

 under a little cluster of two or more spikelets ; and in Maydese it 

 is the rhachis of the spike which disarticulates under each female 

 spikelet. In GramiuesB generally, however, the articulation, 

 whether of the rhachis, of the pedicel, or of the rhachilla, is 

 usually under the fertile spikelets or flowers only ; under the 

 males it is apt to be very obscure or quite obsolete. 



The fertile flower is above spoken of as only apparently ter- 

 minal, because the presence of the palea and a slight obliquity 

 tend to show that the floral axis is not really the continuation of 

 the rhachilla, but, as in Poacese, a secondary or axiUary branch. 

 Doell says, indeed, that a continuation of the rhachilla behind 

 the palea has been observed in a species of Panicum ; but I have 

 never succeeded in meeting with it in any PanicacesB. In the 

 tribe Oryzeae, where there is no two-nerved palea, it may still re- 

 main a matter of doubt whether the floral axis is or is not distinct 

 from the rhachilla — whether the uppermost scale is a glume on 

 the rhachilla or a palea at the base of the floral axis. The pre- 

 sence or absence of a central nerve is not an absolute test ; for it 

 is occasionally, though very rarely, absent in the lower glumes. 



Panicacese have never more than four glumes, the uppermost 

 one usually enclosing or subtending the fertile flower, though in 

 some Andropogonese it is excessively reduced or even quite 

 obsolete or rudimentary. The next under it may be empty like 

 the lower ones, or may enclose a palea, a rudimentary flower, or 

 a perfecb male flower, and in Beckmannia, and a very few species 

 or individuals of Setaria and Panicum, this lower flower may be 

 hermaphrodite, but usually, if not always, sterile. The two lower 

 glumes when present are always empty. "Where the spikelets 

 are unisexual, the females have only the single terminal flower, 

 the males most frequently two flowers, both witii perfect 

 stamens. 



