PANICE^. 



161 



barbed bristles above the base; heads 5-6 mm. long, beside the 

 spines, containing 3-5 spikelets. Spikelets ovate-lanceolate. 5 mm. 

 long, first glume 4 mm. long, 5-nerved, second like it only a little 

 shorter; palea 5 mm. long, 2-nerved, containing 3 stamens; fertile 

 floret ovate-lanceolate, acuminate, -i mm. long or more. 



'' Variable in the lengtli of the spike, tlie size of the spikelets. the 

 length of the lowest glume, tlie number of glume-nerves, and in the 

 development of the palea in staminate or 

 neutral flower." Grisebach's Flora of 

 the West Indies. 



North Carolina to Florida and Texas, 

 West Indies, Mexico to Brazil, tropical 

 Africa, East Indies. 



4. C. tribuloides L. Sp. PI. 1050 

 (1753). BuR-GKASS. San"d-bue. Hedge- 

 hog-grass. C. Carolinianus Walt. Fl. 

 Car. 79 (1788). 



A branched ascending annual, 30-60 

 cm. high. Sheaths loose, about as long 

 as the internodes; ligule ciliate; blades 

 linear, flat or conduplicate, about 10 cm. 

 long, 5 mm. wide. Spike usually oblong, 

 with 6-20 sjjherical heads about 6 mm. 

 long, besides the spreading barbed spines; 

 heads more or less downy. SjDikelets 2-3 

 in eacii head, ovate, 5-7 mm. long, first 

 and second glumes subequal, 5-nerved 

 and 3-nerved respectively, third glume 

 (palea of the neuter floret) hyaline, 2- 

 nerved; fertile floret ovate, briefly acu- 

 minate, about 5 mm. long. 



New Jersey, U. S. Dept. Agricul. Fig. 29.— Cenc/iorus tribuloi- 

 122, identified by Vasey and Scribner; 6,^*same iu^^'section^^'c,' 



Michigan, Cooley; Illinois, Beal 25. spikelet. (Scribuer.) 



Xumber 349, of Dr. E. Palmer, Sonora, Mexico, is a more 

 slender plant, the heads scarcely more than half the size of 



