322 CONTRIBUTIONS FROM THE NATIONAL HERBARIUM. 
as long as the spikelet, 5-nerved; second glume and sterile lemma subequal, 7 to 
9-nerved, the lemma subtending a rather firm palea and a staminate flower; fruit 3 to 
3.5 mm. long, 1.5 to 1.7 mm. wide, subacute, smooth and shining, but very obscurely 
pubescent at the apex. 
The Brazilian species, P. repandum Nees, is the only known species related to 
P. obtusum. 
DISTRIBUTION. 
Sandy or gravelly soil, mostly along the banks of rivers, arroyos, and irrigation 
ditches, western Missouri and Colorado to Texas and Arizona and southward to south- 
ern Mexico. 
Missouri: Kansas City, Bush 1832, 3107 (Gray Herb.). 
Kansas: Stanton County, Hitchcock Pl. Kan. 572. 
Texas: Dallas, Hall 827, Reverchon 1079 and in 1879; Kerrville, Heller 1741, Smith 
in 1897; Waller County, Thurow in 1898 and 1906; Llano, Plank in 1892; 
Amarillo, Ball 1139; Fort Worth, Ward in 1877; Abilene, Tracy 7935; Bexar 
County, Jermy 6; San Antonio, Plank in 1893; El Paso, Jones 4168; Fort 
Davis, Havard in 1881; Kingsville, Piper in 1906; Texline, Griffiths 5612; 
without locality, Buckley in 1881; Nealley in 1887. 
Ox.LAHoMA: On the False Washita, Palmer 370 in 1868. 
Cotorapno: Rocky Ford, Griffiths 3309; Canyon City, Shear 975; Trinidad, Shear 
in 1900; Las Animas County, Chase 5406. 
New Mexico: Cabra Spring, Pease in 1878; McCarty, Munson & Hopkins in 
1889; Socorro, Plank 76, Vasey 
in 1881; Gray, Skehan 94, 97; 
Cimarron Canyon Griffiths 
5542; Roswell, Earle 301; Las 
Cruces, Wooton 1068; Silver 
City, Metcalfe 749; Mesilla, 
Wooton 64; Mesilla Park, 
Hitchcock 3830; Deming, 
Hitchcock 3763; Grant County, 
Blumer 205, Smith in 1897; 
White Water, Mearns 2308; 
without locality, Vasey in 18815 
Wright 2092. 
Arizona: Moki Reservation, Hough 80; Beaver Creek, MacDougal 569, Rusby 
864, 8921; Toumey in 1891; Santa Rita Mountains, Griffiths 3405, 6959, 7288, Grif- 
fiths & Thornber in 1902; St. Johns, Griffiths 5196; Holbrook, Zuck in 1896; 
Tucson, Griffiths 1514, 1546; Benson, Griffiths 2006, Hitchcock 3737; Pearce, 
Griffiths 1935; Sulphur Spring Valley, Forbes 1645; Patagonia, Hitchcock 3646, 
3661; Fort Huachuca, Wilcox in 1894; San Pedro River, Mearns1130; Bisbee, 
Mearns 925; San Bernardino Ranch, Mearns 773; near Monument 88 (Mexi- 
can Boundary), Mearns 1845. 
Mexico: La Ventura, Nelson 3908; Saltillo, Palmer 394 in 1898; Chihuahua, 
Nelson 6352, Pringle 476; Nogales, Griffiths 6800; Durango, Palmer 175 in 1896; 
Conception del Oro, Palmer 266 in 1904; San Luis Potosi, Palmer 590 in 1898, 
Parry & Palmer 960, Schaffner 148; Faral, Schumann 1714. 
Fig. 362.— Distribution of P. obtusum. 
~©, 193. Panicum hemitomon Schult. 
Panicum waltert Ell. Bot. S. C. & Ga. 1: 115. 1816, not Pursh, 1814. ‘‘ Grows in 
damp soils. On Charleston neck, common. Macleod’s pond, 64 miles from Savan- 
nah, on the Ogechee road.’’ The type, in the Elliott Herbarium, consists of the 
upper portions of two culms, one sterile, the other withanimmature panicle. Attached 
to this specimen is a label which reads: ‘‘Panicum Walteri mihi. Hab. in humidis 
