40 MH. a. BENTHAM ON GBAMINEiE. 



however, as far as I have observed, usually sterile ; and a similar 

 character is to be found in some species or varieties of Setaria, 

 and very rarely in Panioum itself, nest to which the genus appears, 

 to be best placed. The synonym JoacJiimia, Ten., given by Kunth, 

 was a name intended for it by Tenore, but I believe never actually 

 published. Tenore figures the plant as a BecTcmannia. 



7. Panicum:, Linn., after deducting Ichnanthus, Oplismenus, 

 Setaria, and several smaller genera, remains one of the larger, and 

 probably the largest, among tropical Grrasses, and is still in many 

 respects polymorphous. In habit and inflorescence it may be 

 confounded sometimes with Paspalum, sometimes with Arundi- 

 nella, or even with some Agrostese. Generally speaking, it may 

 be easily recognized by technical characters ; but the most marked, 

 the yery small size of the lowest empty glume, is not quite con- 

 stant ; for in a few species this glume is wholly deficient as in 

 Paspalum, whilst in a few others it is of the size of the second 

 glume ; the hardening also of the fruiting glume and palea is in 

 some species very slight. There is nothing, however, sufficiently 

 definite or constant in these exceptional species to mark them out 

 as intermediate genera ; and here, as in so many other cases of 

 large genera of Cyperaceae and G-raminesB, we must admit the 

 existence of forms which must be placed in one or the other of 

 allied genera from considerations of convenience rather than of 

 strict character. Taking the genus Panicum within the limits we 

 have ascribed to it, nearly 800 supposed species have been pub- 

 lished : Steudel enumerates 716 ; Doell has 134 Brazilian ones, 

 Fournier 97 Mexican, Nees 44 South-African ; I described 54 

 Australian ones ; and they are rather numerous in tropical Africa 

 and Asia ; but a considerable number are repeated in several or 

 even in all of these Moras, and a large proportion of Steudel's 

 species are mere synonyms or blunders. The total number of 

 fairly distinct species can therefore scarcely be estimated at much 

 above 250. These have been variously grouped, chiefly according 

 to their inflorescence ; and no less than eighteen supposed genera 

 have been at different times separated from it, but are now re- 

 united, either as being founded on insufficient, uncertain, or even 

 mistaken characters, or as being, in our opinion, more conveniently 

 regarded as sections than as genera. But, even as sections their 

 limits are often as far from being absolutely definite as are those 

 of the whole genus. The following eleven are those which have 

 appeared to be the most distinct ; but they are aU more or less 



