34 CONTRIBUTIONS FROM THE NATIONAL. HERBARIUM. 



De Graminibus Paniceis, Trinius divides Panicum into six sec- 

 tions: a, Digitaria (Syntherisma) ; b, Paspalum; c, Brachiaria; 

 d, Orthopogon (Oplismenus) ; e, Jubaria (Ghaetochloa, Pennisetum, 

 Hymenachne, Valota, and various other genera of Paniceae having 

 plumelike panicles) ; and /, Miliaria (Anthaenantia, Tricholaena, 

 and species from other genera). The sections are all artificial, Brachi- 

 aria especially so, including, as it does, species of Paspalum, Pan- 

 icum, Thrasya, and Echinochloa, the common character of the assem- 

 blage being the simple racemes. Four species having reversed 

 spikelets are included, Panicum falciferum Trim, P. polyphyllum 

 R. Br., P. glumare Trim, and "P. granulare LaM.," the last included 

 as a variety under " Panicum brizoides Retz." (P. punctatum Burm.). 



In Panicearum Genera, the work which Grisebach cites, the species 

 with a single raceme (Paspalum decumbens and species of Thrasya) 

 are placed in the new section Harpostachys, leaving the remainder 

 under Brachiaria, an assemblage scarcely less heterogeneous than be- 

 fore. Two more species with reversed spikelets, Panicum isachne 

 Eoth (P. erucaeforme J. E. Smith) and P. plantagineurn Link, are 

 added, but the reversed position is not mentioned, nor are these six 

 species grouped together. Since there is nothing in either work to in- 

 dicate which species should be considered the type of Brachiaria, it 

 seems best to follow Grisebach and take as the type B. erucaeformis. 

 Grisebach, however, did not intentionally select this species as the 

 basis of the genus; it was the only species of Trinius's section which 

 occurred in the Russian Empire, the grasses of which he was de- 

 scribing. Grisebach does not mention the reversed spikelets. This 

 character, first noted as generic by Nash x (" flowering scale with its 

 opening toward the rachis ") , confines the genus to B. erucaeformis 

 and its allies. The genus so limited is somewhat diverse, but taken 

 as a whole the morphological resemblances of the species segregated 

 on the combined characters of racemose inflorescence and reversed 

 position of solitary subsessile spikelets having a well-developed first 

 glume indicate a fairly natural genus, the extremes being united by 

 a series of intermediate species. 2 



Like several other genera of Paniceae, Brachiaria includes species 

 that appear to be closely related to outlying species of Panicum. 

 Panicum, helopus Trim, from the Mascarenes, has solitary spikelets 

 in strict racemes, and papillose-rugose, awn-tipped fruit as in B. 

 meziana and other species of Brachiaria, but the spikelets are placed 

 as in Panicum fasciculatum and its allies. Urochloa panicoides 

 Beauv., from Mauritius, is, judging from the poor illustration and in- 



1 In Small, Fl. Southeast. U. S. 50, 80. 1903. 



2 For further history of Brachiaria as section and genus, see Chase, Proc. 

 Biol. Soc. Washington 24: 126-129. 1911. 



