HITCHCOCK AND CHASE NORTH AMERICAN PANICUM. 



225 



wide, acuminate, often somewhat involute toward the apex, narrowed toward the 

 rounded base, the upper surface sparingly pilose toward the base and margins, the 

 lower surface densely velvety- villous; panicles short-exserted, 7 to 11 cm. long, 

 nearly as wide, rather densely flowered, the axis sparingly villous near the base, the 

 branches spreading; spikelets 2 mm. long, 1 mm. wide, elliptic, somewhat obovate at 

 maturity, obtuse, pubescent with soft, spreading hairs; first glume one-fifth the 

 length of the spikelet, obtuse or obscurely pointed; second glume and sterile lemma 

 equal, scarcely equaling the fruit at maturity, obtuse or slightly pointed; fruit 1.7 

 mm. long, 1 mm. wide, elliptic, subacute. 



Autumnal form erect, after the maturity of the primary panicle bearing at the mid- 

 dle nodes a few appressed or ascending 

 fascicled branches scarcely longer than 

 the primary internodes, the reduced 

 blades flat or somewhat involute at the 

 tips, ciliate. 



DISTRIBUTION. 



Prairies and dry open woods, Ala- 

 bama to Texas. 



Alabama: In the vicinity of Mo- 

 bile, Mohr in 1895 and 1897. 



Louisiana: Without locality, Hale 

 (Gray Herb.). 



Texas: Waller County, Hitchcock 1171, 1195, 1226, Thurow 9, 11; Montgomery 

 County, Thurow in 1905; Hockley, Thurow in 1893 and 1906; Swan, Reverchon 

 4163; Houston, Ravenel in 1869; Del Rio, Plank 41; without locality, Nealley 

 in 1884 and 1887. 



Fig. 233.— Distribution of P. thurowii. 



^ 130. Panicum olivaceum. 



sp. nov. 



description. 



Vernal culms olive green, erect or somewhat spreading at base, 20 to 40 cm. high, 

 velvety- villous with short hairs, the nodes bearded; sheaths villous like the culm, 

 mostly shorter than the internodes; ligules 3 to 4 mm. long; blades rather stiffly 

 erect or ascending or some of the lower spreading, 4 to 7 cm. long, 5 to 8 mm. wide 

 (the uppermost erect, 1 to 3 cm. long), puberulent on both surfaces, also more or less 

 short-villous above, and often with longer villous hairs toward the base; panicles 3 to 



7 cm. long, ovate, the flexuous branches spreading, 

 short spikelet-bearing branchlets in the axils; spike- 

 lets 1.9 to 2 mm. long, 1 mm. wide, obovate, sub- 

 acute, papillose-pilose; first glume one-fourth to one- 

 third the length of the spikelet, usually pointed; 

 second glume scarcely equaling the fruit and sterile 

 lemma; fruit 1.6 mm. long, 1 mm. wide, subacute. 



Autumnal form upright or becoming decumbent- 

 spreading, freely branching from the lower and middle 

 nodes before the maturity of the primary panicle, the 

 reduced branches appressed, or in the decumbent culms curved upward; blades 

 reduced, flat, 1 to 2 cm. long, 2 to 4 mm. wide, usually conspicuously ciliate. 



Type U. S. National Herbarium no. 823209, collected February, 1888, at Coban, 

 Department of Alta Vera Paz, Guatemala, altitude 1,400 meters, by H. von Tuerck- 



FiG. 234. — P. olivaceum. 

 type specimen. 



From 



41616°— VOL 15—10- 



-15 



