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. ‘ 
AtaBaMA: In the vicinity of Mo- 
bile, Mohr in 1895 and 1897. 
Lourstana: 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. 
Y 180. 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, | 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- 
41616°—vo1 15—-10-——15 
Fig. 234.—P. olivaceum. From 
type specimen. 
