42 MB. G. BENTHAM ON GBAMINEiE. 



are few : P. semialatum, Br., is widely spread over the Old World, 

 for I am unable to distinguisli tlie Asiatic Ooridochloa, Nees, and 

 the South- African Bluffia, Ness, from Brown's Australian species ; 

 P. Qayanimii Kunth, is confined to tropical Africa; P. leueo- 

 pJicBvm, H. B. K., is frequent under various names in the tropical 

 and subtropical regions of the Wew and the Old World. It is a 

 very variable species ; and specimens gathered at difierent stages 

 of development look very different from each other, but are not 

 separable into marked varieties. It was included by Beauvois in 

 his genus Urochloa, and appears to have been the type of the 

 proposed genera Aciearpha, Eaddi, JUriacIme, Philippi, and Holo- 

 setum and Mesosetum, Steud., and is probably the principal ele- 

 ment of Presl's supposed genus Alloteropsis. 



(3) Diplaria. This section is proposed for a few American species 

 with a simple terminal spike-like inflorescence. The spikelets 

 are sessile along the rhachis in two rows and distichous, as in the 

 section AnastropJius of Paspalum, from which Diplaria differs 

 technically in the presence of the small outer glume characteristic 

 of Panicum. It comprises P. rottloellioides, H. B. K., P. exaratwni 

 and P.ferruginemi, Trin., P.pappopTiorum, Nees, and a few others. 



(4) Thrasya, distinguished as a genus by Kunth, has a simple 

 terminal spike-like inflorescence as in Diplaria ; but the rhachis is 

 more or less dilated as in the section Ceresia of Paspalmm, and 

 the spikelets, sessile along the midrib, although really alternate 

 and biseriate, have all the appearance of being in a single row. 

 The species are few, all American, and include, besides the ori- 

 ginal Thrasya paspaloides, Kunth, the P. ansafmn, Trin., which 

 is scarcely specifically distinct from it, P. tTirasyoides, Trin., P. 

 petrcBum, Trin., and perhaps two or three others. The P. petrmmi 

 forms the genus Tylothrasya of Doell, which he characterizes by 

 a callous thickening of the pedicel like that of Mrioohloa ; but the 

 plant is in all other respects too closely allied to the typical 

 Thrasya to be generically separated, and the callosities are slightly 

 prominent in various species of Panicum. 



(5) Harpostachys. The inflorescence is again simple and spike- 

 like ; but the spike is more or less falcate, with the spikelets 

 crowded in two or four rows along one side of the slender rhachis 

 as in Chlorides, and the common peduncles are usually long and 

 often clustered two or three together in the upper axils. To 

 this section belong P. monostachymi, H. B. E., P. decumhens, E. 

 et Schult., and P. subfalcatum, Doell. 



