HITCHCOCK AND CHASE—NORTH AMERICAN PANICUM. 47 
wide, the main axis much exceeding the erect branches, the axes densely clothed with 
short pubescence having long, stiff hairs intermixed, the short-pediceled spikelets 
somewhat crowded; spikelets 5 to 6 mm. long, about 2 mm. wide, fusiform, pointed, 
short-attenuate at base, pilose; first 
glume clasping, more than half the 
length of the spikelet, acute, 3 to 5- 
nerved; second glume and sterile lemma 
exceeding the fruit, 5-nerved, often 
obscurely reticulate; fruit 3.7 to 3.8 
mm. long, about 2 mm. wide, elliptic, 
apiculate. 
DISTRIBUTION. 
Prairies and open ground, especially 
on low land along streams, often a weed 
in waste ground and cultivated fields, FiG. 29.—Distribution of P. teranum. 
Texas and northern Mexico. 
This is sparingly cultivated under the name of Colorado grass. 
Texas: Dallas, Reverchon 1226 in Curtiss N. Amer. Pl. 3607A; Corsicana, Rever- 
chon 2228; Pierce, Tracy 7748; Victoria, Plank 73; Austin, Plank 31; Har- 
vester, Thurow in 1898; Wallisville, Wallis in 1880; Goliad County, Lea in 
1874; San Antonio, Bush 1198, Havard in 1882; Corpus Christi, Hitchcock 163. 
Mexico: Monterey, /Titchcock 5540. 
Dichotomiflora.— Annual plants with smooth culms, mostly large, spreading pani- 
cles, the branchlets short and appressed along the ascending or rarely spread- 
ing main branches; ligule membranaceous below, densely ciliate above, 1 to 
3mm. long; spikelets glabrous, narrow, acute or acuminate, 2 to 5 mm. long, 
the first glume one-fifth to one-fourth as long, truncate or with a broadly trian- 
gular tip; fruit smooth and shining. 
Panicles narrow, less than 1 cm. wide........-.-...--------- 16. P. vaseyanum. 
Panicles open, the branches usually ascending. 
Fruit acuminate; culms with a long, rooting base... ... - . 19. P. elephantipes. 
Fruit not acuminate. 
Sheaths papillose-hispid.......-.....-.------------- 18. P. bartowense. 
Sheaths glabrous. ......-.-.------------++++-+++----- 17. P. dichotomiflorum. 
16. Panicum vaseyanum Scribn. 
Panicum vaseyanum Scribn.; Beal, Grasses N. Amer. 2:140, 1896. The only speci- 
men cited is ‘‘Mexico, Pringle 1415.” The type specimen, in the National Herba- 
rium, was collected in the State of Chihuahua, in 
‘‘Wet places, pine plains, base of Sierra Madre,’’ Sep- 
tember 30, 1887, by C. G. Pringle. 
DESCRIPTION. 
Plants spreading, branching at base and at the lower 
and middle nodes, glabrous throughout; culms 50 to 
70 cm. long, somewhat compressed; sheaths shorter 
than the elongated internodes; ligules 1 to 2mm. long; 
blades 5 to 20 cm. long, 3 to7 mm. wide, linear, scarcely 
narrowed at the folded or enveloping base; panicles 
terminal and from the axils of the upper leaves of the 
main culms and large branches, narrow, 4 to 7 cm. long, less than 1 cm. wide, partially 
included, equaled or exceeded by the erect uppermost blade; spikelets short-pediceled, 
narrowly ovate, 2.5 mm. long, 1.1 to 1.2 mm. wide, subacute; first glume about one- 
Fic. 30.—P. vaseyanum. From type 
specimen. 
