Chase — Notes on Genera of Panicecz. IV. 



121 



side) instead of on the back as in Panicum, Paspalum and, in more or 

 less pronounced form , in all other genera of the Paniceae. The fruit differs 

 from that of Panicum in having less indurated lemma and palea, the 

 margins of the lemma Hat. Doell (in Mart. Fl. Bras. 2 : 2 17:5. 1.S77) 

 states that in this group of plants the caryopsis has a linear hilum, but 

 the specimens in the National Herbarium are not mature enough to per- 

 mit of verification of this statement. The genus is confined to the tropics 

 of the western hemisphere, Brazil being the center of distribution, two 

 species occurring in the West Indies. 



Besides Mesosetum proper the genus contains a well-marked section. 



First ghune awnless; lower floret neuter . . . . Mesosetum proper. 

 First glume awned ; lower floret staminate . . . Section Bifaria. 



Mesosetum proper. 

 This contains the following species : 



Mesosetum rottboellioides (H. B. K. ) Hitchc. Contr. Nat. Herb. 12 : 



211. 1900. Based on 

 Panicumrottbocllioides 

 H. B. K. 



Panicum rottboelli- 

 oides H. B. K. Nov. 

 Gen. & Sp. 1 : 96. pi. 

 32. 1816. "Crescit in 

 humidis ripa? Orino- 

 censis inter Maypures 

 et montem Sipapo." 



Mesosetum cayen- 

 nense Steud. Syn. PI. 

 Glum. 1 : 118. 1854. 

 (See above. ) 



Fig. 3. 



Mesosetum rottboellioides. 



(Spikelet, first glume, second glume, sterile lemma and 



fruit x 10 diam.) 



Mesosetum Wrightii 



Hitchc. Contr. 

 Wright 3859 no. 559961 in the U. S. 



Nat. Herb. 12:211. 1909. 

 National Herbarium." 

 This species is known only from Cuba. 



Mesosetum exaratum (Trim). 



Panicum exaratum Trim Gram. Pan. 100. 1826. "Brasil. (Langs- 

 dorff. )" The type specimen, in the Trinius Herbarium, is labeled 

 "Panicum exaratum in. In pratis paludosis S. da Lapa. Brasil. leg. cl. 

 de Langsdorff." 



Panicum pappophorum Nees, Agrost. Bras. 104. 1829. ' Habitat 

 * * * provinciae Piauhiensis." The type specimen, in the Munich 

 Herbarium, bearing the name and locality as published, was collected by 

 Martius. 



