FLOWERING PLANTS AND FERNS OF ARIZONA 91 



6. Lemmas webbed at base, the web sometimes obscure in P. interior (7). 

 7. Panicle branches slender, reflexed at maturity, the lower branches in 

 2's; culms rather soft at base; leaf blades relatively short, flat, mostly 



2 to 4 mm. wide 6. P. reflexa. 



7. Panicle branches stiffly ascending, spreading, or drooping but not re- 

 flexed; culms firm toward base (8). 

 8. Panicles 10 to 30 cm. long, broad, the branches spreading or drooping; 

 culms decumbent at the reddish base; ligule 3 to 5 mm. long. 



7. P. palustris. 

 8. Panicles less than 10 cm. long, the branches short, ascending; culms 

 erect, densely tufted; ligule less than 1 mm. long. 



8. P. INTERIOR. 



6. Lemmas not webbed at base (9). 



9. Lemmas glabrous or scabrous; spikelets scarcely flattened, the lemmas 

 rounded on the back at maturity; sheaths usually scabrous. 



12. P. XEVADENSIS. 



9. Lemmas pubescent on the nerves and sometimes on the internerves; 

 spikelets flattened, the lemmas keeled at maturity (10). 

 10. Leaf blades lax or soft, usually flat; spikelets usually 3-flowered. 



11. P. RUPICOLA. 

 10. Leaf blades firm, involute, erect; spikelets 5- or 6-flowered, about 

 8 mm. long; plants incompletely dioecious (11). 



11. Ligule very short 9. P. fexdleriaxa. 



11. Ligule 5 to 7 mm. long 10. P. loxgiligula. 



1. Poa bigelovii Vasev and Scribn. in Vasey, Desc. Cat. Grasses U. S. 



81. 1S85. 

 Coconino, Mohave, Yavapai, Pinal, Maricopa, and Pima Counties. 

 1,000 to 3,000 feet, open ground. Oklahoma and western Texas to 

 Nevada, Arizona, southern California, and northern Mexico. 



2. Poa annua L., Sp. PL 68. 1753. 



Devil's Canyon and Sacaton (Pinal County), Camp Creek (Mari- 

 copa County), Fort Huachuca (Cochise County), 1,200 to 5,000 feet. 

 open ground, lawns, and waste places. Newfoundland to Alaska, south 

 to Florida, Arizona, and California; also in tropical America at higher 

 altitudes; introduced from Europe. 



3. Poa pratensis L., Sp. PI. 67. 1753. 



Apache County to Coconino County, south to Cochise and Pima 

 Counties, medium to high altitudes, moist meadows and open woods. 

 Canada and throughout the United States, except in dry or hot situa- 

 tions; introduced from Europe. 



This, the well-known Kentucky bluegrass, is an extremely variable 

 species differing markedly in appearance depending on the location 

 where it is found. Although the plant is sometimes depauperate and 

 sometimes very tall and coarse, the florets are relatively uniform in 

 having a pronounced cobweb, densely pubescent keel, and lateral 

 nerves. 



4. Poa glaucifolia Scribn. and Williams, U. S. Dept. Agr., Div. 



Agrost. Cir. 10: 6. 1899. 

 San Francisco Peaks (Coconino County), moist places at high 

 altitudes, July to August. Wisconsin to New Mexico and Arizona. 



5. Poa compressa L., Sp. PL 69. 1753. 



White Mountains, 8,600 feet (Apache County), Pinaleno Mountains 

 (Graham County), open ground, meadows, and waste places. New- 

 foundland to Alaska, south to Georgia, Tennessee, Oklahoma, 

 New Mexico, Arizona, and California; introduced from Europe. 



