HITCHCOCK AND CHASE NORTH AMERICAN GRASSES. 



59 



said by the authors to be very closely related to C. ecMnatus. The description 

 indicates a depauperate specimen of that species with short spikes, and with 

 but two spikelets in a bur. Doell, who examined an authentic specimen, states l 

 that it is a form of C. ecMnatus in which the spikelets are slightly longer than 

 the involucre. 



Cenchrus macrocarpus Ledeb. ; Steud. Nom. Bot. ed. 2. 1 : 317. 1840. A 

 garden name given as a synonym of C. ecMnatus L. 



CencM'Us brevisctus Fourn. Mex. PI. 2 : 50. 1886. " Yalle de Orizaba 

 ( Schaffn [er] n. 198 in herb. Feanq., Boueg[eau] n. 3140 . . . Bott[eei] n. 

 133.)." Bourgeau's no. 3140 in the National Herbarium, bearing the name in 

 Fournier's hand, and in the herbarium of the Botanical Garden of Petrograd is 

 about the average form of C. ecMnatus. In his key to the species of Cenchnis, 

 Founder places C. ecMnatus with C. myosuroides and C. multiflorus Presl (a 

 species of Pennisetum) , as having the inner involucre cleft nearly to the base. 

 Among the specimens cited under C. ecMnatus are Liebmann's nos. 468, 471, and 

 472. The specimens in the Copenhagen Herbarium are those studied by Four- 

 nier. 2 All three are ordinary C. ecMnatus. In this species and its allies the in- 

 volucre is irregularly cleft ; sometimes one of the clefts (besides that on the side 



Fig. 12. — Cenchrus echinat-us. From Hitchcock 9379, Jamaica. 



toward the axis) reaches well toward the base. This is not constant in burs on 

 the same spike. It seems probable that in his study of the specimens Fournier 

 referred to C. ecMnatus those specimens in which he observed burs with a single 

 deep cleft, while those in which a deep cleft was not noted he referred to C. 

 brevisetus. The short bristles, which gave the specific name, are short in com- 

 parison to those of G. pallidus (C. pilosus), which in Fournier's arrangement is 

 grouped with G. brevisetus. 



Cenchrus ecMnatus brevisetus Scribn. in Millsp. Field Mus. Bot. 2: 26. 1900. 

 Based on Cenchrus brevisetus Fourn. 



DESCRIPTION. 



Plants annual ; culms ascending from a geniculate or decumbent base, often 

 rooting at the lower nodes, branching from the base and usually from the lower 

 nodes, commonly 25 to 60 cm. long, sometimes as much as 1 meter long, com- 

 pressed, scabrous below the spike, otherwise glabrous; sheaths loose, mostly 



1 In Mart. Fl. Bras. 2 2 



2 See p. 45. 



310. 1877. 



