412 CONTRIBUTIONS FROM THE NATIONAL HERBARIUM. 



DESCRIPTION. 



A stout, erect, cespitose, long-lived perennial with stout rhizomatous base, usually 

 in isolated bunches, but occasionally in continuous patches in the southern portion 

 of its range; culms erect, stout, unbranched, 60 to 80 cm. high; sheaths close, strongly 

 striate; blades abundant below and more sparing above, flat, variable in width, mostly 

 2 to 3 mm. wide, with regularly disposed papillose hairs on the edges; ligule a ciliate 

 fringe of white hairs, about 1 mm. long; spikes loose, variable, often 3 cm. long by about 

 8 mm. wide or sometimes only 1.5 cm. long, and then resembling those of Bouteloua 

 filiformis; spikelets 7 to 10 or sometimes even as much as 11 or 12 mm. long, consisting 

 of 2 florets, the lower perfect, the upper either pistillate or perfect and producing 

 mature seed more often than the lower one; glumes sharply acuminate, the first 4, 

 the second 5 to 6 mm. long; lemma smooth, bone-like, 7 to 8 mm. long, 3-awned, the 

 lateral awns about 1 mm. and the central 2 to 3 mmJong; palet inclosing the caryopsis, 

 scarcely awned, but 1 mm. shorter than the lemma; floret of the same form and texture 

 as that of the lower, 9 to 10 mm. long, with lateral awns 5 to 6 mm. and the central 

 about 1 to 2 mm. longer; palet not differing materially from that of the lower floret; 

 caryopsis about 4 to 5 mm. long, 0.75 to 1 mm. wide, flattened, the scutellum covering 

 four-fifths of the ventral surface. (Plate 81.) 



As stated elsewhere this species grows in the upper foothills and mountains and 

 reaches higher altitudes than the closely related B. filiformis with which it is commonly 

 mixed. It differs from that species mainly in being a taller, coarser plant through- 

 out. Its leaves are larger and wider, the culms are larger and stouter, the papillose 

 hairs upon the edges of the leaves are more pronounced and obvious, and the spikes 

 are longer. However, upon plants of B. radicosa may be found some spikes which 

 might pass for B. filiformis, and plants of B. filiformis grown in exceptionally favorable 

 localities have spikes as long as some forms of B. radicosa. It is only in consideration 

 of an aggregation of characters that they can well be distinguished, yet they are in my 

 mind perfectly worthy of being kept apart and are easily distinguishable in the field 

 and usually upon the herbarium sheet as well. Bouteloua radicosa is found in 

 rather high situations from Arizona and New Mexico to southern Mexico along the 

 continental highland, and extends westward in important quantities especially into 

 Jalisco and Guerrero. As in B. filiformis there is a great variation in the spikelet. 

 More commonly it is the second floret that is perfect instead of the first. Tonduz 

 13745 & is referred here doubtfully on account of the very small spikes. 



HERBARIUM SPECIMENS. 



Arizona: Wilcox, Fort Huachuca in 1894. Jones 562, Bowie. Griffiths & Thornber 

 220, Santa Rita Mountains. MacDougal 798, Dos Cabezas. Nealley, Rincon 

 Mountains. 



California: Orcutt in 1884. 



New Mexico: Wright 2024. Smith, Mangas. Rusby 460, Burro Mountains. 



Mexico: Meatus 855, south of Bisbee. Tovmsend & Baker 226, Colonia Garcia'. 

 Bourgeau 450. Pringle 1436, Guerrero; 8567, Federal District. Brandegee 2 and 

 57, Cape region, Lower California. Palmer 1354, Coahuila, Nuevo Leon; 301 and 

 188, Rio Blanco; 115a, Chihuahua; 547, Durango. Nelson 2265, San Marcos, 

 Guerrero; 1443 and 1258, valley of Oaxaca; 6258, Colonia Garcia, Chihuahua; 

 6305, Sierra Madres, Chihuahua. Rose 2672, Colotlan, Jalisco. 



a See under B. americana. ° Herb. Inst, fis.-geogr. Costa Rica. 



Explanation of Plate 81. — a, Habit sketch of Bouteloua radicosa; b, spikelet;c, d, lemma and palet of 

 first floret; e and/, lei-.ma and palet of second floret; g, prolongation of rachilla; h, two views and cross- 

 section of caryopsis; i, portion of leaf blade.- o, One-fourth natural size; b-g, scale 5; ft, scale 7.5; i, scale 2.5. 

 From Griffiths 7181 and photograph. 



