Chase — Notes on Genera of Panice<r. IV. 127 



Urochloa Pal. [deBeauv.] * * * Streptostachys Desv., Echinochloa 

 Pal." In the body of the work (p. 125) the first species included under 

 section Brachiaria is Panicum decumbens Roem. & Schult. ( Paspalum 

 decumbens Poir. ), the species which later (Mem. Acad. St. Petersb. VI. 

 Sci. Nat. 3 : 2 227. 1834) is the first included under section Harpostachys 

 of Trinius. This is followed by Panicum thrasyoides and P. cultratum 

 (species of Thrasya), several species of Panicum (in the stricter sense) 

 and of Echinochloa; P. holosericeum and P. argenteum, in which the 

 spikelets are in the reversed position and which are the first species under 

 section Brachiaria as later used by Trinius, are here only the seventeenth 

 and eighteenth species under that section. In the " Panicearum Genera " 

 (Mem. Acad. St. Petersb. VI. Sci. Nat. 3 : 2 194. 1834), which Grisebach 

 cites, Trinius makes Brachiaria the eighth section of Panicum, Uar- 

 postachys, to which are relegated the species with a single raceme earlier 

 included in Brachiaria, being the seventh. The characters now assigned 

 to Brachiaria are: Simple, alternate racemes, the partial axes angled 

 (usually 3-angled) ; sessile or short-pediceled, glabrous, pilose, or lanate, 

 awnless spikelets, imbricated in 2, 3, or 4 series. No species is here men- 

 tioned, but under " VIII Brachiaria" (pages 233-247) this purely arti- 

 ficial division contains thirty diverse species referable to Brachiaria (as 

 here limited), Echinolaena, and the greater number to Panicum. Since 

 there is nothing in either work to indicate which species should be con- 

 sidered the type, it seems best to follow Grisebach' s choice when he 

 established Brachiaria as a genus. His choice, to be sure, was guided 

 by the fact that Panicum eruciforme was the only one of the group which 

 occurred in the Russian Empire, but even so, it would be unwise to reject 

 his type and arbitrarily to choose another. Panicum eruciforme is in- 

 cluded, under the name "Panicum Isachne Roth !" by Trinius in the first 

 subdivision of his section Brachiaria as limited in the ' ' Panicearum 

 Genera." Later in the " Graminum Supplementa " (op. cit. 4 : 1 103. 

 1836) he states that P. Isachne should be called Panicum eruciforme. 

 Trinius' first three species, P. holosericeum R. Br., P. argenteum R. Br. 

 and P. serratum Spreng. , are of that peculiar group of Old World species 

 with reversed spikelets clothed with silvery hairs more or less aggregated 

 across the middle of the second glume and sterile lemma, and having a 

 well-developed first glume, which, together with Leucophrys, appear to 

 be a connecting link between Eriochloa and Brachiaria. In the present 

 state of our knowledge it is difficult to say whether these species fall the 

 more naturally into Brachiaria or into Leucophrys. 



Grisebach does not mention the reversed position of the spikelets in 

 Brachiaria, and later (Goett. Abh. 7 : 263. 1857) transfers to this genus 

 Panicum prostratum Lam. (P. reptans L. ), a species in which the spike- 

 lets are not in the reversed position. In the " Flora of the West Indies" 

 (page 545. 1864) Grisebach uses " Brachiaria Tr." as a section of Pani- 

 cum, including under it Panicum pas paloides Pers. [P. geminatum Forsk. 

 is intended] and three species of Echinochloa. 



