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408 CONTRIBUTIONS FROM THE NATIONAL HERBARIUM. 



I can not, however, from the insufficient fragment before me be certain about it. 

 The leaves are shorter and ratber more rigid than in that species. 



Eutriana bromoides Trin. Gram. Unifl. 241. 1824, not Kunth 1833. 7t is more than 

 probable that tbe species to which Trinius applied this name is B. americana, although 

 the first synonym cited is Aiheropogon bromoides Roem. & Schult. The other two 

 synonyms are Aristida americana L. and Bouteloua litigiosa Lag., and the plant described 

 is from the West Indies. Kunth a has in effect expressed the same view. 



Bouteloua elatior Griseb. Fl. Brit. W. Ind. 537. 1864. A portion of the type, Wull- 

 schlagel 619 and 660, Antigua, in the Grisebach Herbarium, and a photograph are 

 before me. It is typical of Aristida americana L. 



Aiheropogon americanus Fourn. Mex. PI. 2 : 139. 1851. Based upon Aristida ameri- 

 cana L. 



Bouteloua triathera Benth. Journ. Linn. Soc. Bet. 19 : 104. 1881. Presumably based 

 on Tr lather a americana Desv . | _- /*- «- 



Bouteloua americana Scribn. Proc. Acad. Phila. 1891 : 306. 1891. Scribner bases 

 this name on "Aristida americana Sw. Obs. 41. t. [2.] f. 2. (1791) ", on the supposition 

 that this was distinct from A. americana L., citing Munro's statement, & that the 

 Linnaean A. americana was a true Aristida and the species named Aristida dispersa 

 by Trinius. But, as has been shown, Linnseus's type specimen is a Bouteloua. 

 Swartz does not give this as one of his own species, but gives a reference that leads to 

 Linnaeus's species. Swartz's illustration shows that he correctly interpreted the 

 species. Hence Scribner's name is, in the last analysis, based on Aristida americana L. 



DESCRIPTION. 



A spreading, ascending, or erect, smooth annual; flowering culms mostly erect, 

 freely branched, 20 to 30 cm. high; sheaths striate, smooth, short, close; blades nar- 

 row, involute, acuminate, bearing numerous papillose hairs on the edges toward the 

 base, there merging into the very narrow ligular ring; spikes about 2 cm. long, very 

 lax, 3 to 6 or 7; spikelets 5 to 7, about 3 mm. apart, not pectinate but loose, and lying 

 at a narrow angle with the rachis; glumes pronouncedly keeled and strongly hispid, 

 rather abruptly acuminate, the first about 3 mm., the second about 4 mm. long; 

 lemma smooth, shining, and bone-like on the back, 3-awned, the lateral awns less than 

 1 mm. long, the central projecting about 2 mm. farther; palet 2-nerved, with 2 short 

 awns, nearly as long as its lemma; rudiment consisting of a modified lemma of 3 awns 

 about 9 mm. long, united into a hard small scale at the base and faced by a small 

 2-neryeTrlIdlmentary palet; caryopsis not seen. (Figure 57.) 



The group comprising Bouteloua americana and the five species here following is a 

 very difficult one and^a great many names have been applied to the different species 

 owing to a difference of opinion among authors as to generic and specific limitations 

 and to the disregard of, the principle of priority as well as to a misunderstanding or 

 neglect of the earlier descriptions. 



Bouteloua radicosa as interpreted here is fairly well marked off. It is a large, 

 robust, ahnost woody based plant with wide, strongly papillose-hairy leaves. Bou- 

 teloua repels as here interpreted is not so common as has been supposed. It is easily 

 recognized ^by its glaucous aspect and by its lack of papillose hairs. The species 

 appears to be confined to the Pacific coast region of central and southern Mexico. 



Bouteloua americana also is well characterized by its narrow spikes and annual 

 habit. 



It is B. Jiliformis and B. hetcrostega that present the greatest difficulties. They are 

 very difficult to segregate, but that is simply another way of acknowledging that we 

 do not know the species well enough. 



o Enum. PI. 1 : 281. 1833, under E. bromoides. 

 b See above under Aristida americana L. 



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