256 CONTRIBUTIONS FROM THE NATIONAL HERBARIUM. 
43. ECHINOCHLOA Beauv. Ess. Agrost. 53. pl. 11. f. 2. 1812. 
KEY TO THE SPECIES. 
Spikelets awnless or mucronate only; spikes simple, rather remote. 1. E. colonum. 
Spikelets more or less awned ; spikes more or less compound, approxi- 
mate. 
Sheaths hispid................-..-..00.- 22222202 e eee eee eee 4. E. waltert. 
Sheaths glabrous. 
Awns conspicuous. 
Awns as much asd cm. long; panicle long and dense.. 5. E. holciformis. 
Awns less than 2 cm. long; panicle mostly not over 15 
cm. long, not dense..............2-----2--2e0-- 6. E. spectabilis. 
Awns not longer than the body of the spikelet. 
Panicle erect; branches stiffly ascending or appressed; 
awns mostly less than 1 mm. long............. 2. E. zelayensis. 
Panicle nodding, rather soft and lax; awns 1 to 5 mm. 
IONg... 0. eee eee eee eee eect e ee eee 3. E. sabulicola. 
1. Echinochloa colonum! (L.) Link, Hort. Berol. 2: 209. 1833. 
Panicum colonum L. Syst. Nat. ed. 10. 870. 1759. 
Type locality, Jamaica, the type specimen from Browne. 
Rance: Warmer parts of both hemispheres. 
HERBARIUM SPECIMENS FROM MEXIco: 
Lower CaA.iForNiA: Santa Agueda, Palmer 223 in 1890. San José del Cabo, 
Brandegee 26 in 1890, 38 in 1899. 
Sonora: Oputo, Hartman 189. Nogales to Cocospora Ranch, Griffiths 6832. 
Yaqui River, Palmer 13 and 14 in 1869. Sierra de Alamos, Rose, Standley 
& Russell 12984. Guaymas, moist roadside, Hitchcock 3560; Palmer 51 and 
202 in 1887. Hermosillo, by ditch in meadow, Hitchcock 3580; weed in 
field, Hitchcock 3620. 
Curavuanua: Sdénchez, along railway, Hitchcock 7690. Chihuahua, depression in 
mesa, Hitchcock 7780. Santa Eulalia Plains, Wilkinson 42. 
Smvatoa: Topolobampo, Rose, Standley & Russell 13265. Mazatlén, moist field, 
Rose, Standley & Russell 14039. San Blas, Rose, Standley & Russell 13424. 
Culiac4n, rich bottom lands, Palmer 1542 in 1891. Rosario, along the river, 
Rose, Standley & Russell 14574; Rose 1544. 
Duraneco: Torreén, field, Hitchcock 7552. Durango, in water of ditch, Hitchcock 
7655. Tlahualilo, Pittier 478. 
Coanumta: Saltillo, along irrigation ditch, Hitchcock 5592; field, Hitchcock 5599. 
Nuevo Le6n: Monterey, irrigation ditch, Hitchcock 5548. 
Teric: Acaponeta, moist ravine, Rose, Standley & Russell 14250; Rose 1923. 
San Luis Porosi: Cardenas, irrigated field, Hitchcock 5750. 
Jauisco: Rfo Blanco, Palmer 193 in 1886. San Nicolas, cornfield, Hitchcock 7224. 
GuaANAJuATO: Irapuato, moist sandy-clay plain, Hitchcock 7413. Ac&mbaro, 
along ditch, Hitchcock 6941. 
QUERETARO: Querétaro, water of irrigation ditch, Hitchcock 5831. 
Couma: Colima, in swampy ground and along water courses, Palmer 169 in 1897. 
Caldras, along railway, Hitchcock 7020. 
Pursia: Tehuacan, along ditch, Hitchcock 6052. Cholula, Nicolas in 1910. 
1Dr. E. L. Greene called attention to the fact that the specific name is not an 
adjective, and suggested that it is probably a genitive plural. The word appears to 
be contracted from colonorum, genitive plural of colonus, a husbandman or a colonist. 
Dr. J. A. Nieuwland has kindly searched Latin authorities and verifies this conclu- 
sion, though there appears to be no direct authority for the word colonum. 
