126 



Chase — Notes on Genera of Pan ice se,. IV. 



Description. — Inflorescence of one to many, usually dense, racemes 

 along a common axis; spikelets solitary, sometimes in pairs, short pedi- 

 celed or subsessile in two rows on one side of a narrow, usually hairy 

 rachis, the pedicels often clothed with long stiff hairs [the "involucre " 

 of Kunth], the back of the fertile lemma turned from the rachis; spike- 

 lets dorsally compressed, more or less pubescent, stipitate by the length- 

 ening of the internode of the rachilla below the second glume into a more 

 or less ring-like, usually dark-colored callus, the first glume reduced to a 

 minute sheath about this internode and adnate to it; second glume and 

 sterile lemma equal or nearly so, acute or acuminate, the lemma usually 

 enclosing a hyaline palea and sometimes a staminate flower; fruit indu- 

 rated, less so than in Panicum, minutely papillose-rugose, the lemma 

 mucronate-pointed or aristate, sometimes pubescent at the apex, the 

 margins slightly inrolled. Perennial herbs with linear leaves and terminal 

 panicles of few to many racemes, confined to the warmer temperate and 

 tropical regions of both hemispheres. 



This genus approaches Leucophrys and Brachiaria through such species 

 as Panicum nigropedatum Munro, P. argenteum R. Br., and P. serratum 

 R. Br. in which the first glume is well developed above the more or less 

 stipitate base. 



13. Genus BRACHIARIA (Trim) Griseb. 



Brachiaria Griseb. in Ledeb. Fl. Ross. 4 : 469. 1853. Grisebach here 

 raises "Panicum sect. Brachiaria Trin." (Mem. Acad. St. Petersb. VI. 

 Sci. Nat. 3 : 2 194. 1834) to a genus, including under it a single species 



B. eruciformis ( Smith ) Griseb. based on Pani- 

 cum eruciforme Smith (Sibth. Fl. Graec. 1 : 

 44. pi. 59. 1806). " In arvis circa Junonis 

 teinplum in insula Sarno." The plate is a 

 good representation of the species and fully 

 identifies it. The enlarged portion of the 

 raceme ( f. A) shows that the spikelets are 

 placed with the first glume toward the axis. 

 This species we here take as the type of the 

 genus. Roemer & Schultes (Syst. Yeg. 2 : 

 42<>. 1817) misspell the name " cruciforrne," 

 and in this form also it appears in the Index 

 Kewensis under Brachiaria. 

 Grisebach cites not the first work in which Trinius proposes the sub- 

 genus Brachiaria, but a later work, in which Trinius includes a some- 

 what different group of species from those included in his first establish- 

 ment of the section in "De Graminibus paniceis " (pages 51 and 125. 

 L826). Here (p. 51) the section is diagnosed as follows: Racemes simple, 

 regularly or irregularly alternate; spikelets oblong (rarely lanceolate), 

 either in regular series and imbricated or laxly disposed ; lower glume 

 manifest, awnless. Under it are included "Thrasya Kth.? * * * 



Fig. 5. 



Brarhiaria eruciformis. 



(Two views of spikelet and 



fruit x 10 diam.) 



