PAXICEAE 



47 



Paniflu smaller, not (jver 1-3 the 

 length of the plant. 

 First glume more than 3-4 the 

 length of the second; spike- 

 let 4 mm. long. 



l-ir.-;l glume 1-2 to 2-3 the length of 

 the second; .sjiikelet not over 

 3.3 mm. long. 



Perennials. 



Stems n(jt bulbo-js nor rhizomatous. 



Sterile palea enlarged and hardened at 

 maturiij- expanding the spikelet; 

 glumes acute: an introduced plant 

 in the fields. 



Sterile palea not enlarged; glumes 

 acuminate; native plant in the 

 mountains. 

 Stems bulbous at base or rhizomatous. 

 Glumes acuminate. 



Spikelet 3 to 5 mm. long; 1st glume 

 long acuminate to cuspidate; 

 rhizomes several inches long 

 and scaly. 

 Spikelets 6 to 8 mm. long; 1st glume 

 acute; rhizomes shorter. 

 Glumes obtuse or merely acute, never 

 acuminate. 

 Culms from a rootstock, not bulbous. 

 Culms from an enlarged bulbous base. 



!i. /'. painj)i)iostim. 

 111. /'. hirticaule. 



I', liiaiis. 

 I'. haUii. 



13. P. virgutum. 



14. P. haianlii. 



15. P. plenum. 

 K). P. bulbosum. 



1. Panicum obtusum II. K. K. Vine Mesquite Grass. 

 Common at lower levels in the southern part of the State and up 

 to about (iOOO feet altitude in the northeastern corner. It does not 

 occur frequently in the m( urtains. In the Sonoran Zone. 



2. Panicum heileri Nash. Known from a single collection 

 in the Mcgollun l\J<>nntains at about 7-500 feet altitude. In the 

 Transition Zone. 



3. Panicum scribnerianum Xash. Collected but once; at Las 

 Vegas. Ill the Upper Sonoran Zone. (?). 



4. Panicum fasciculatum chartiginense (Sw.) Doell. An 



introduced field weed folhcted once at SocoiTo. Lower Sonoran 

 Zone. 



5. Panicum arizonicum Scribn. and Merr. A small annual 

 not uncommon in the foothi'ls of the mountains of the southern part 

 of the State after the snmmei- rains. Upper Sonoran Zone. 



6. Panicum dichotomiflorum Michx. Known from a 

 single collection near Las Cruces. Lower Sonoran Zone. 



