HITCHCOCK AND CHASE — NORTH AMERICAN PANICUM. 



65 



DESCRIPTION. 



Plants erect, simple or nearly so, or sometimes branching and decumbent at base, 

 15 to 70 cm. high; culms papillose-hispid to glabrous, nodes spreading-hispid ; sheaths 

 papillose-hispid, but sometimes sparsely so; blades 5 to 15 cm. long, 4 to 13 mm. wide, 

 often cordate at base, sparsely hispid or nearly glabrous, ciliate toward the base; 

 panicles exserted, 5 to 15 cm. long, scarcely one-third the entire height of the plant, 

 rather many-flowered, the branches ascending, the lower usually narrowly so, scabrous 

 but not pilose, bearing rather short and 



appressed-pediceled spikelets along half 

 to two-thirds their length, the glabrous 

 pulvini inconspicuous; spikelets 2.7 to 

 3.3 mm. long, 1 to 1.1 mm. wide 

 (smaller in occasional specimens), 

 lanceolate-fusiform, acuminate, typi- 

 cally reddish brown; first glume half to 

 three-fourths the length of the spikelet, 

 acuminate, the midnerve scabrous 

 toward the apex; second glume slightly 

 longer than the sterile lemma, both 

 much exceeding the fruit, strongly 



many-nerved, the midnerves scabrous toward the summit, the palea of the sterile 

 floret small, nerveless; fruit 2 mm. long, 1 mm. wide, elliptic, a scar sometimes 

 showing on either side at base. 



This species is variable; the Mexican specimens are mostly fairly typical, but the 

 more northern ones are often rather freely branched or the panicles are less strict or 

 the spikelets not reddish. 



In the following Mexican and Central American specimens the spikelets, though 

 reddish brown and borne on strict branches, are only 2.2 to 2.5 mm. long. Mexico: 

 Colima, Palmer 14, 143, and 145 in 1897; Alamos, Palmer 690 in 1890; Territorio de 

 Tepic, Rose 3351. Nicaragua: Without locality, Flint in 1868. 



Fig. 47.— Distribution of P. Urticaule. 



DISTRIBUTION. 



Rocky or sandy soil, Texas to southern California and south through Mexico; also 

 in the Galapagos Islands. 



Texas: El Paso, Jones 4212; without locality, Nealley in 1887. 



Washington: Bottomland near Bingen, Suksdorf 2330. This is probably intro- 

 duced, as it is far out of its range. 



New Mexico: Organ Mountains, Wooton in 1907, Standley in 1906; Florida Moun- 

 tains, Mulford 1012, 1078; Mangas, Metcalfe in 1897, Smith in 1898; Rio Gila, 

 Greene 258; Hillsboro, Metcalfe 1442; San Luis Mountains, M> earns 2093. 



Arizona: Tucson, Griffiths 1520, 3358, Hitchcock 3481, 3494, 3509, Pringle in 1881; 

 Santa Rita Mountains, Griffiths 7005, 7194, Griffiths & Thornier 4, 28, 256; 

 Salero Mountains, Griffiths 6123; Santa Catalina Mountains, Griffiths 7146; 

 Huachuca Mountains, Eolzner 1659; Fort Huachuca, Wilcox in 1894; Pearce, 

 Griffiths 1938; Cochise, Griffiths 1918; Phoenix, Griffiths 7317; Patagonia, 

 Hitchcock 3658, 3675; Benson, Hitchcock 3730; near monument 82, Mearns 

 1905; near Mexican boundary, Mearns 738, 767. 



California: Sierra Nevada Mountains, Lemmon in 1875; Jamacha, Canby 6 in 1894. 



41616°— vol 15—10 5 



