HITCHCOCK AND CHASE—NORTH AMERICAN PANICUM. 15 
surface or sparingly papillose-hispid beneath, often with a thin, cartilaginous, white 
margin; panicles usually long-exserted and much exceeding the leaves, 6 to 20 cm. 
long, rather narrowly flabellate in outline, the few branches stiffly ascending, bearing 
short, appressed branchlets with approximate spikelets on short, appressed pedicels; 
spikelets 3 to 3.7 mm. long, 1.1 to 1.5 mm. wide, turgid; first glume half to two-thirds 
the length of the spikelet, acuminate, 3 to 5-nerved; second glume and sterile lemma 
strongly 5 to 7-nerved; fruit 1.7 to 2 mm. long, 1 to 1.3 mm. wide, oval, obtuse, dark 
olive brown at maturity. 
The following specimens have looser panicles than typical and spikelets only 2.8 to 
3.2 mm. long, the two Plank specimens having also laxer blades. These appear to be 
intermediate between P. filipes and P. hallit but rather nearer the latter. Trxas: 
Abilene, Tracy 7941, Del Rio, Plank 44, 57. 
Leiberg’s no. 5916, collected on cinder cones, is a depauperate form, scarcely 10 cm. 
high. 
DISTRIBUTION. 
Dry prairie, rocky and gravelly hills and canyons and in bottomlands, and irri- 
gated fields, Texas to Arizona and south to central Mexico. 
Texas: Texline, Griffiths 5600; Baird, Letterman in 1882; Austin, Hall 816, Stiles 
in 1884; Abilene, Bentley in 1899, Tracy 7950; Colorado, Tracy 7945; Big 
Springs, Tracy 7953; Kimble County, Reverchon 1682; Kerrville, Smith in 
1897; San Antonio, Hitchcock 
219, Plank 46, 53; Corpus 
Christi, Hitchcock 221; Olmito, 
Tracy 9338; Spofford, Griffiths 
6288; Del Rio, Plank 72 in 
part; Midland, Tracy 7952, 
7954; Guadalupe Mountains, 
Bailey 719; Fort Davis, Nealley 
in 1893, Marfa, Havard 23; 
Sierra Blanca, Nealley in 1893; 
El Paso, Vasey in 1881; with- 
out locality, Nealley in 1887. 
New Mexico: Cimarron Canyon, Griffiths 5504; Roswell, Earle 302; Carlsbad, 
Tracy 8200; Organ Mountains, Hitchcock 3783; Las Cruces, Griffiths 7408; 
Dona Ana County, Wooton & Standley 3983; Deming, Hitchcock 3762; Grant 
County, Metcalfe 807, Smith in 1896 and 1897. 
Arizona: San Francisco Peaks, Leiberg 5916; Ash Fork, Griffiths 7357; Prescott, 
Toumey in 1894; Clifton, Davidson 31a, 414a; Mescal, Griffiths 1813; Santa 
Rita Mountains, Griffiths 3388, Griffiths & Thornber 238, 309; Patagonia, 
Hitchcock 3706; Paradise, Blumer 1683; Huachuca Mountains, Holzner Inter- 
nat. Bound. Comm. 1566; without locality, Lemmon in 1883. 
Mexico: Tamaulipas, Palmer 554 in 1907; Coahuila, Palmer 1338 in 1880; Chi- 
huahua, Pringle 376. 
Fig. 63.—Distribution of P. hallii. 
36. Panicum lepidulum sp. nov. 
DESCRIPTION. 
Plants solitary or in small tufts, erect, 25 to 70 cm. high; culms usually producing 
one or two erect branches from the lower nodes, sparsely papillose-pilose to merely 
scabrous toward the summit; sheaths longer than the short lower internodes, shorter 
than the middle and upper ones, papillose-hispid, the hairs ascending; ligules about 
2mm. long; blades erect, or spreading at the apex, 7 to 30 cm. long, 5 to 10 mm. wide, 
scarcely narrowed to the more or less infolding base, flat or folded, sparsely papillose- 
pilose to nearly glabrous on both surfaces, glaucous on the upper surface; terminal 
