36 CONTRIBUTIONS FROM THE NATIONAL HERBARIUM. 



lemma turned from the axis; spikelets dorsally compressed, sometimes turgid; 

 first glume well developed ; second glume and sterile lemma equal or nearly so, 

 5 to 7-nerved, the lemma inclosing a hyaline palea and sometimes a staminate 

 flower; fruit indurate (in the type species smooth and shining), usually papil- 

 lose-rugose, the lemma usually apiculate or awn-tipped, the margins inrolled. 

 Annuals or perennials with usually flat blades, the culms often decumbent 

 and rooting at the lower nodes ; confined to the warmer temperate and tropical 

 regions of both hemispheres. 



KEY TO THE SPECIES. 



Spikelets pubescent. 



Plants annual ; spikelets 2.5 mm. long, the pubescence about evenly dis- 

 tributed 1. B. erucaeformis. 



Plants perennial ; spikelets 3.5 to 4.5 mm. long, the pubescence conspicuously 

 uneven. 

 Fruit with a pubescent awn about 1 mm. long . . . 2. B. ophryodes. 



Fruit awnless 3. B. ciliatissima. 



Spikelets glabrous. 



Plants perennial ; spikelets about 3 mm. long ; fruit awn-tipped. 



4. B. meziana. 

 Plants annual ; spikelets 4 mm. long or more ; fruit awnless. 



Rachis 1 to 1.5 mm. wide; spikelets about 4.5 mm. long, not turgid, 



nor flat-beaked beyond the fruit 6. B. plantaginea. 



Rachis 2 mm. wide ; spikelets about 4 mm. long, turgid, flat-beaked 

 beyond the fruit 5. B. platyphylla. 



C 



1. Brachiaria erucaeformis (J. E. Smith) Griseb. 



Panicum erucaeforme J. E. Smith in Sibth. Fl. Graec. 1 : 44. pi. 59. 1806. 

 " In arvis circa Junonis templum in insula Samo." The plate leaves no doubt 

 as to the identity of the species. 



Panicum isachne Roth in Roem. & Schult. Syst. Veg. 2 : 458. 1817. " In India 

 orient. Heyne." The type specimen has not been examined, but the descrip- 

 tion identifies the species. 



Panicum caucasicum Trin. Gram. Icon. 3 : pi. 262. 1831. " Figura ad speci- 

 men e Caucaso orientali." The plate identifies the species. 



Panicum wightii Nees, Fl. Afr. Austr. 29. 1841. "In graminosis vallis ad 

 Gekau. . . . (Drege)." Two unpublished names based on East Indian col- 

 lections are cited as synonyms, " Panicum wightianum W.-Arn. et N. ab E. 

 Glum. Ind. or. ined.," and " Panicum Koenigii Herb. Wight n. 14 " ; but since 

 it is to be assumed that Nees drew up his description for the African flora 

 from the Drege specimen, this is taken as the type. The description indicates 

 a small specimen. 



Echinochloa erucaeformis Koch, Linnaea 21: 437. 1848. Based on Panicum 

 erucaeforme. 



Panicum pubinode Hochst. : A. Rich. Tent. Fl. Abyss. 2: 363. 1851. "In pi. 

 Schimp. Abyss., sect. III. no. 1855 . . . Crescit in convalle fluvii Tacazzg 

 . . . (Schimper)." The spikelets are described as purple-tinged. It is on 

 this color difference that the author distinguishes it from P. erucaeforme. 



Brachiaria erucaeformis Griseb. in Ledeb. Fl. Ross. 4: 469. 1853. Based on 

 Panicum erucaeforme J. E. Smith. 



Panicum isachne var. mexicana Beal, Grasses N. Amer. 2: 114. 1896. "Speci- 

 men seen was cultivated from seed obtained in Mexico by U. S. Dept. Agricul., 

 1887." Beal gives " P. eruciforme Sibth. . . . var. mexicana Vasey, ined." 



