FEB. 1903. PLANTS YUCATAN.* MILLSPAUGH & CHASE. 



39 



bristles. Glumes of the spikelet 4, the second auriculate and the third 

 lyre-shaped near the base; fruiting glumes indurated, mucronate, the 

 margins of the floral glume inrolled as in Panicum. Grain dorsally 

 compressed, enclosed in the fruiting glumes, free. Stamens 3. 



Setatariopsis auriculata (Fourn.) Scribn. ibid. 

 Setaria auriculata Fourn. 



Panicles exserted, 5-15 cm. long, 1-1.5 cm. wide; branches alternate, 

 ascending, 8-20 mm. long; axis and rachis hirsute. Spikelets 1.4x2.9 



mm., light green, ovate, apparently 

 acute by the involution of the glumes. 

 glabrous on short hispid pedicels, each 

 bearing a slender flexuous antrorsely- 

 barbed awn, 6-12 mm. long. First 

 glume the length of the spikelet, 

 broader than high, obtuse with the 

 apex inrolled at maturity, 7-nerved; 

 second nearly the length of the third, 

 broadly ovate, obtuse, auriculate near 

 the base, i3-nerved; third narrower, 

 somewhat lyre-shaped and corky at the 

 base," the margins becoming sub- 

 coriaceous at maturity, u -nerved, 

 subtending a minute hyaline palea; 

 fruiting glumes pale stramineous, 



1.2x2 mm., ovate, mucronate, transversely rugose. Grain pinkish 

 white, ovoid, acute, .9x1.3 mm.; in section truncate plano-convex. 

 Hab. Merida, July n, 1865, Schott 591, 592, Hacienda Sara- 

 gossa, Sept. 9, 1865, 621 ; common in old fields about Izamal, Sept., 

 Gaumer 2479, &49 (tyP e f tne g enus )> Chichankanab, 



CENCHRUS L. Sp. PI. 1049. 



Inflorescence spicate, axis flexuous, scabrous or hispid; spikelets 

 in a's-6's subtended by a short-pediceled involucre of rigid connate 

 spines which is deciduous with them at maturity. Glumes mostly 4, 

 first sometimes wanting; fruiting glumes indurated, but less so than 

 in Panicum, the floral glume not inrolled at the margins and having a 

 short prominent keel eafch side of the midnerve at the base. Grain 

 dorsally compressed, enclosed in the fruiting glumes, free. Stamens 3. 



Basal bristles few, stout 

 Basal bristles numerous: 



Lobes of -the involucre interlocking: 

 Spines 3-6 mm., retrorsely barbed 

 Spines 6-12 mm., antrorsely barbed 

 Lobes of the involucre erect or spreading: 

 Shorter than the spikelets 

 Equaling or exceeding the spikelets: 

 Spikelets 4-5 in each involucre, 5.7 mm. 

 Spikelets 2-3 in each involucre, 6.5 mm. 



tribuloides. 



viridis. 

 pallidus. 



brevisetus, 



echinatus. 

 insularis. 



Cenchrus viridis Spreng. Syst. 1:301. 



Spikes long exserted, 48 crn. long, of 20-50 or more crowded 

 involucres, 6x6 mm. including bristles, on pilose pedicels; the 7-8 



