HITCHCOCK AND CHASE — NORTH AMERICAN GRASSES. 



55 



nodes very short, the long leafless upper part of the culm appressed-pubescent ; 

 sheaths overlapping, appressed-pubescent, often becoming glabrate in age ; 

 ligule ciliate, scarcely 1 mm. long; blades 1.5 to 2.5 cm. long, about 1.5 mm. 

 wide, conspicuously distichous, stiffly spreading at a uniform angle and usually 

 about 1 cm. apart, involute, sharp-pointed, glabrous on the outer surface, 

 scabrous on the inner, sometimes with a 

 few long hairs at the base ; spike long- 

 exserted, 2 to 3 cm. long, bearing usually 

 5 to 7 spreading yellow burs, the slender 

 axis glabrous, its summit prolonged beyond 

 the uppermost bur as a sharp point 2 to 4 

 mm. long ; burs, including the spines, 5 to 6 

 mm. long, nearly as broad, the body of the 

 bur about 3 mm. long and 2 mm. wide, 

 puberulent, the outer spines subterete, 

 swollen at the base, the lobes of the in- 

 volucre about 10, prolonged into sharp, 

 slender spines, pilose on the inner surface toward the base, retrorsely barbed 

 toward the tip ; spikelet solitary, terete or thicker than wide, about 3.3 mm. 

 long and 1.3 mm. wide ; first glume very narrow, often obsolete ; second glume 

 obtuse, shorter than the subequal pointed sterile and fertile lemmas ; fruit 

 turgid, the palea puberulent on the upper half. 



Fig. 



9. — Cenchrus distichophyllus. 

 From the type specimen. 



DISTRIBUTION. 



Dry sandy pine barrens, Province of Pinar del Rio, Cuba. 

 Cuba: Laguna Jovero, Shafer 10717. San Julian, Ledn 6941; Lamas 7475. 

 " Western Cuba," Wright 3475. 



In Robinson's Flora of the Galapagos Islands 1 some sterile specimens col- 

 lected on Albemarle Island are doubtfully referred to Cenchrus distichophyllus. 

 Stewart 2 also refers two of his collections to this species, one of which, his 

 no. 1235, sent to the National Herbarium, is a sterile specimen of Sporobolus 

 virginicus (L. ) Kunth. The other specimens are doubtless the same species. 



4. Cenchrus pilosus H. B. K. 



Cenchrus pilosus H. B. K. Nov. Gen. & Sp. 1 : 116. pi. 36. 1816. " Crescit in 

 planitie herbida Provinciae Novobarcellonensis (Llanos de Nueva Barcellona), 

 juxta Villa del Pao," Venezuela. The type specimen has not been examined, 

 but the description and the plate identify it as a small, exceptionally pilose 

 specimen of the species later described as C. pallidus. 



Cenchrus pallidus Fourn. Mex. PI. 2: 50. 1886. "In locis ruderalis, Hacienda 

 de Santa Cruz pr. Tehuantepec in prov. Oajacensi, . . . (Liebm. n. 465)." The 

 type specimen, Liebm ann 465, in the Copenhagen Herbarium, bears the name 

 in Fournier's hand. 



DESCRIPTION. 



Plants annual ; culms often rather stout, compressed, usually decumbent at 

 base and rooting at the lower nodes, 20 to 100 cm. long, simple or sparingly 

 branching below, scabrous below the inflorescence, otherwise glabrous ; sheaths 



1 Proc. Amer. Acad. 38 : 118. 1902. 



2 Botanical Survey of the Galapagos Islands, Proc. Cal. Acad. Sci. IV. 1 : 31. 

 1911 



