Chase — Notes on Genera of Panicece. IV. 119 



VI. Sci. Nat. 3 : 2 240. 1834) places P. uncinatum in the section 

 Brachiaria. 



Kunth (Rev. Gram. 1:54. 1829) doubtfully refers to Echinolaena his 

 own E. polystachya, together with Panicum nemorosum Sw . , P. naviculare 

 Nees (both of which belong in Irhnanthus) and P. brachystachyum Nees 

 and P. procurrens Nees. In his synoptical heading the character " gluma 

 superior echinato-glochidata " would exclude all but E. polystachyn. In 

 the Enumeratio (Enura. PL 1 : 173. 1833) Kunth again doubtfully includes 

 these species and adds Panicum loliaceum Bert., probably referable to 

 Ichnanthus. 



While the uncinate and ventricose second glume of the mature spikelet 

 of this species makes it look very different from spikelets of E. inflexa, 

 the paired spikelets, the primary fertile, the secondary abortive or rudi- 

 mentary, placed face to face, the back of the primary one turned toward 

 the rachis, and the essentially like structure of the spikelet to that of E. 

 inflexa show the two species to be congeneric. The second glume becomes 

 indurated and spiny only as the spikelet nears maturity; the immature 

 spikelets resemble those of E. inflexa. The sterile spikelet is often reduced 

 to a mere rudiment, is sometimes wanting, and is rarely developed like 

 the primary spikelet. In the fifty specimens of this species in the National 

 Herbarium none are found without some of these sterile spikelets in the 

 racemes. 



From the description, Echinolaena madagascarensis Baker, a species 

 which we have not seen, appears to belong unmistakably to this genus. 



10. Genus MESOSETUM Steud. 



Mesosetum Steud. Syn. PI. Glum. 1 : 118. 1854. This is based on a 

 single species, M. cayennense Steud. (1. c.) " Leprieur legit in Cayenne." 

 The type specimen, labeled "Mesosetum cayennense Steud. Cayenne. 

 Leprieux, 1825," in the Steudel Herbarium at Paris, is found to be the 

 same species as Panicum rottboellioides H. B. K. Steudel earlier (Flora 

 33 : 228. 1850) mentions the name in a paper on the progress of his work 

 on the "Synopsis plantarum." The generic description as given by 

 Steudel is faulty and misleading. He evidently became confused as to 

 the morphology of the parts of the spikelet. But reading his description 

 with a dissected spikelet of P. rottboellioides under the microscope one 

 can see that this is what Steudel is trying to describe. It seems likely 

 from his description of the ' ' flosculus hermaphroditus ' ' that he mistook 

 the sterile lemma with the fertile floret enfolded for the hermaphrodite 

 floret (that is mistaking the fertile lemma for the "second valve" of the 

 floret). Steudel' s statement that M. cayennense approaches Panicum 

 mesocomum Nees is further misleading. For this reason the name Meso- 

 setum has been referred to various sections of Panicum but never, so far 

 as we can find, to the group containing Panicum rottboellioides, until so 

 used by Hitchcock (Contr. Nat. Herb. 12 : 211. 1909). Bentham (Linn. 

 Soc. Journ. Bot. 19 : 42. 1881) says that Panicum leucophaeum H. B. K. 

 (which is Panicum insulare (L. ) Meyer, Valota insularis (L. ) Giwtee-) " 



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