HITCHCOCK AND CHASE—NORTH AMERICAN PANICUM. 81 
of the sterile floret about as long as its lemma; fruit 2.9 to 3 mm. long, 1 mm. wide, 
elliptic, acute, only very obscurely rugose, minutely puberulent at the apex. 
Type U. S. National Herbarium no. 495701, collected September 18, 1903, ‘‘at 
Mangas Springs, 18 miles northwest of 
Silver City, Grant County, New Mexico, 
by O. B. Metcalfe (no. 739), altitude 
4,770 feet.”’ 
This species is related to P. bulbosum 
from which it is distinguished chiefly 
by the creeping rootstock and decum- 
bent, not corm-like, base of the culms. 
Specimens lacking the base may be 
recognized by the compressed culm, 
scarcely scabrous blades, shorter first 
glume, and only very obscurely rugose 
fruit, appearing smooth except under 
a high power lens. Many specimens of this species have been distributed as P. 
avenaceum but an examination of the type specimen of the latter, together with the 
statement in the original description that the base is bulbous, shows it to be the 
same as P. bulbosum. 
Fig. 70.—Distribution of P. plenum. 
DISTRIBUTION. 
Moist places in rocky hills and canyons, Texas to Arizona, south to southern Mexico. 
Texas: Kerrville, Heller 1898; Colorado, Tracy 8224; without locality, Nealley 
in 1887. 
New Mexico: Organ Mountains, Vasey in 1881; Wooton 2017; Mangas Canyon, 
Smith in 1896; Mangas Springs, Metcalfe 738, 739; Mangas, Metcalfe 6, 80 in 
part, J. K. Metcalfe in 1897, Smith in 1896; Greenwood Canyon, Smith in 
1896; Las Cruces, Griffiths 7400, 7401; ‘‘from Western Texas to El Paso,” 
N. M., Wright 786. 
Arizona: Santa Rita Forest Reserve, Griffiths 3427; Fort Huachuca, Wilcor in 
1894; Patagonia, IMitchcock 3649; Dos Cabezas, MacDougal 789; Mustang 
Mountains, Pringle 7 in 1884 (Hitchcock Herb.); without locality, Emersley 
in 1890. 
Mexico: Chihuahua, Wilkinson in 1885; Durango, Palmer 741 in 1896; Faral, 
Schumann 1733; Orizaba, Bottert 160; Las Cuevas, Hartman 170. 
41. Panicum bulbosum H. B. K, 
Panicum bulbosum H. B. K. Nov. Gen. & Sp. 1: 99.1815. ‘“‘Crescit in Nove His- 
pani scopulosis et frigidis juxta Santa Rosa, Los Joares et Guanaruato, inter 1070 et 
1360 hexap. altitudinem.’’ The type specimen, from the Bonpland Herbarium in the 
Paris Herbarium, has a well developed corm. The accompanying label reads, “‘ Pani- 
cum bulbosum Kunth Synops. 175. in scopulosis & frigidis. Nova Hisp. alt. 1070- 
1360 hex. No. 4250.””. The spikelets are 3.7 mm. long. 
Panicum avenaceum H. B. K. Nov. Gen. & Sp. 1: 99. 1815.‘ Crescit in regno Qui- 
tensi, in valle amoena Chilloensi et planitie Cachapamba, regione subtemperata, alt. 1340 
hexap.”’ The type specimen, from the Bonpland Herbarium in the Paris Herbarium, 
bears a label with the following data: ‘‘Panicum avenaceum Kunth, Synops. 175. (P. 
bulbosum proximum) in valle amoena Chilla. alt. 1340 h. regn. Quitensis. No. 3016.” 
The base of the specimen is wanting, though the description states that it is bulbous. 
The spikelets are 4mm. long. These slightly larger spikelets and the few hairs on the 
41616°—voL 15—10——6 
