Chase — Notes on Genera of Panioese. TV. 128 



Section Bifaria (Hack.). 



Hackel (Oesterr. Bot, Zeitschr. 17 : 7.">. 1897) establishes Panicum, sec- 

 tion Bifaria with three new Brazilian species, P. bifarium, P. caudicula- 

 i a in and /'. elytrochaetum. Professor Hackel kindly contributed to the 

 National Herbarium a spike from the type specimen of P. bifarium; the 

 other two species have not been examined. The spikelets of P. bifarium 

 have the structure and reversed position characteristic of Mesosetum but 

 differ strikingly in the character of the first glumes. In these the mid- 

 nerve, which (as in most species of Mesosetum proper) is joined by the 

 lateral nerves, is keeled toward the summit of the notched glume and 

 extends into a laterally compressed, sinuous, stout awn, varying from a 

 short point to as long again as the spikelet. The species differs further 

 from those of Mesosetum proper in having a staminate flower in the lower 

 floret. Prof. Hackel points out the relationship of his section Bifaria to 

 Bentham's section Diplaria (P. rottboellioides, P. loliiforme, etc.), and 

 because of this relationship establishes for his three species a section of 

 Panicum instead of a new genus. But unless the boundaries of the genus 

 Panv-um are extended to the limits to which Trinius (Gram. Pan. 1826) 

 stretched them, including Paspalum, Oplismenus, Setaria and other genera 

 recognized as distinct by even the most conservative students of Gram- 

 ineae, the species here referred to Mesosetum with their constant combi- 

 nation of characters and their sharp delimitation from Panicum (there 

 being no intergrading species as between Panicum and Paspalum and 

 between Panicum and Chaetochloa) can not well find place therein. 



The only species of the section Bifariawe have seen is here transferred: 



Mesosetum bifarium (Hack. ). 



Panicum bifarium Hack. Oesterr. Bot. Zeitschr. 47:76. 1S97. " Serra 

 da Baliza ad Cachoeiras da Vargem Grande, 5-1. 1895, Glaziou nr. 22455." 



Bifaria bifaria Kuntze, Gen. PI. 3: 2 359. 1898. Based on Panicum 

 bifarium Hack. Kuntze, apparently without having seen the species, 

 raises Hackel' s section, on account of the lobed and awned first glumes, 

 to generic rank in order to be consistent, he having maintained Oplis- 

 menus and Chaetium as distinct genera, he says, because of this charac- 

 teristic. 



11. Genus LEUCOPHRYS Rendle. 



Leucophrys Rendle, Cat, Afr. PI. Welwitsch 2 : : 193. 1899. This genus 

 is based on a single species, L. mesocoma (Nees) Rendle (op. cit. 194) 

 based on Panicum mesoc'omum Nees, an African species. In this genus 

 the spikelets are placed with the back of the fruit turned from the axis, 

 but, not being strictly racemose, this is not readily observed. The rachilla 

 is produced into a short stipe below the first glume which is separated 

 from the second by the slightly prolonged second joint of the rachilla. 

 The nearly glabrous first glume about as long as the spikelet and the 

 densely silky second glume and sterile lemma, as well as the narrow 



