402 CONTRIBUTIONS FROM THE NATIONAL HERBARIUM. 
tions of the lemma between and outside of the awns; palet of lower floret pubescent 
above, acuminate, that of the second floret with 2 short awns, both about 6 mm. long; 
third floret a simple, undivided awn, a rudimentary lemma consisting of 3 long, pubes- 
cent, scabrous awns, or a well-developed lemma resembling that of the second floret, 
but smaller; caryopsis obovate, about 5 mm. long and 1.5 mm. wide, the scutellum 
covering nearly the entire ventral surface, or only about one-half of it. (PLares 78, 
79, 80, A.) 
This species occurs on familiar collecting ground where the most active botanical 
collectors have worked for years and where the writer collected for about three years 
before finding it. No specimens of it have been found in any of the herbaria exam- 
ined. There are literally scores of acres where it forms one-half to three-fourths of 
the entire vegetation and consequently is, locally, an important economic species. 
I first collected the species in the State of Sonora about a mile south of Nogales, 
Arizona, and subsequently in several situations in northern Sonora and southern Ari- 
zona. I have seen or collected it on the slopes of the Cananea Mountains, in the 
Celero Mountains, where it is most abundant, and in the Santa Rita and Santa Catalina 
Mountains. It is more likely to occur upon southern exposures, especially in the 
Santa Rita and the Santa Catalina Mountains, where it may be neglected for the more 
common and well-known Boutelowa chondrosioides. In some situations southeast of 
Nogales, however, where it grows most luxuriantly, it might be mistaken for a hairy- 
spiked form of B. curtipendula. This in itself indicates a striking variation in the 
general aspect of the species. As indicated in the illustrations, the floral structure 
is fully as variable. 
The type is Griffiths 7269, collected on southern exposures upon the northern slope 
of the Santa Rita Mountains, Arizona, September 17, 1904, 
23. Bouteloua megapotamica (Spreng.) Kuntze. 
Pappophorum megapotamicum Spreng. Syst. Veg. 4: Cur. Post. 34. 1827. The 
type was collected by Sello ‘Rio Grande,’’ Brazil. 
Eutriana multiseta Nees, Agrost. Bras. 413. 1829. This was described from a speci- 
men in the Berlin Herbarium collected by Sello at Montevideo. This specimen 
and a duplicate in the Trinius Herbarium have been examined. See also Kunth, 
Rév. Gram. 2: 449. pl. 138. 1829. 
Pappophorum eutrianoides Trin.; Nees, Agrost. Bras. 414. 1829. Mentioned as a 
synonym under Hutriana multiseta, 
Bouteloua multiseta Griseb. Abh. Ges. Wiss, Géttingen 19: 303. 1879 (Symb. Fl, 
Argent.). Based upon Lutriana multiseta Nees. 
Bouteloua megapotamica Kuntze, Rev. Gen. Pl. 37: 341. 1893. Based upon Pappo- 
phorum megapotamicum Spreng. 
DESCRIPTION. 
A cespitose, erect or ascending, strongly stoloniferous perennial;. culms about 20 
em. high, erect or geniculate af base, not branched; sheaths close, striate, smooth; 
blades rather rigid, abundant below, and often 10 cm. long, but short above, incon- 
spicuously hairy especially on the lower surface, the edges hispid; ligule consisting of 
EXPLANATION OF PLATE 78.—a, Spike of Bouteloua eludens,; b, spikelet; c, lemma of first floret; d, two 
views of palet of samic, one showing pistillate flower; e and /, lemma and palet with perfect flower of second 
floret; g, rudimentary lemma of third floret; h, two views and cross section of caryopsis. a-f, Scale 5; g, 
seale 7.5; h, scale 15. From type specimen. 
EXPLANATION OF PLATE 79.—From type specimen of Boutelowa eludens and photograph taken in Santa 
Catalina Mountains, Arizona. (5 x 7 No. 3076 Farm Management, U.S. Dept. Agr.) 
EXPLANATION OF PLATE 80.—View showing the strong tufty character of Bouteloua eludens, on southern 
exposures in Sabinio Canyon, Santa Catalina Mountains, Arizona, in the latter part of September. B, Bou- 
teloua texana from the vicinity of San Antonio, Texas, where this grass is of minor importance, being usually 
crowded by ranker species. Farther north, in the vicinity of San Angelo, it grows more nearly pure. 
