132 MISC. PUBLICATION 42 3, U. S. DEPT. OF AGRICULTURE 



4. Hilaria mutica (Buckl.) Benth., Linn. Soc. London Jour. Bot. 19: 

 62. 1881. 



Pleuraphis mutica Buckl., Acad. Nat. Sci. Phila. Proc. 1862- 

 95. 1862. 



Yavapai, Gila, Cochise, and Pima Counties, 2,000 to 5,600 feet, 

 dry soil, mesas and hills, May to October. Texas to Arizona and 

 northern Mexico. 



48. AEGOPOGON 



Low, delicate, decumbent, spreading annual with flat, narrow leaf 

 blades and loose racemes of spreading spikelets; spikelets in groups of 

 3, the central one perfect, the lateral spikelets staminate or neuter, 

 falling entire; glumes membranaceous, toothed at apex, the midnerve 

 extending into a delicate awn; lemma and palea thin, longer than the 

 glumes, the nerves extending into awns. 



1. Aegopogon tenellus (DC.) Trim, Gram. Unifl. 164. 1824. 



Lamarckia tenella DC, Cat. Hort. Monsp. 120. 1813. 



Cochise, Santa Cruz, and Pima Counties, open ground in the moun- 

 tains, August to September, 5,000 to 6,000 feet. Southern Arizona 

 to northern South America. 



49. LEPTOCHLOA. Sprangletop 



Annuals or perennials with flat leaf blades and numerous spikes 

 scattered along the common axis; spikelets few- to several-flowered, 

 the upper floret reduced to a small awnless rudiment ; glumes 1 -nerved, 

 the second usually longer and broader than the first; lemmas acute to 

 obtuse, pubescent or pilose on the nerves and sometimes on the 

 internerves. 



Key to the species 



1. Plants perennial; lemmas notched at apex, awnless, the lobes broad, obtuse. 



1. L. DUBIA. 

 1. Plants annual ; lemmas mucronate or awned from between the teeth of a minutely 

 bifid apex, if awnless then not with broad obtuse lobes (2) . 

 2. Sheaths sparsely papillose-pilose; spikelets 1 to 2 mm. long, 3- or 4-flowered. 



2. L. FILIFORMIS. 



2. Sheaths glabrous or scabrous ; spikelets 3 to 12 mm. long, 5- to 12-flowered (3) . 



3. Lemmas 5 to 7 mm. long, mucronate only, scarcely narrowed toward the 



apex, the lateral nerves excurrent 5. L. tjninervia. 



3. Lemmas 3 to 5 mm. long, awned, the awns sometimes minute (4). 



4. Lemmas 2 mm. long, acute, viscid on the back; panicle usually less than 



10 cm. long, tinged with purple 3. L. viscida. 



4. Lemmas 4 to 5 mm. long, acuminate, not viscid; panicle more than 10 

 cm. long, not tinged with purple 4. L. fascicularis. 



1. Leptochloa dubia (H. B. K.) Nees, Syll. PI. Ratisb. 1: 4. 1824. 

 Chloris dubia H. B. K., Nov. Gen. et Sp. 1: 169. 1816. 



Yavapai, Maricopa, Pinal, Cochise, Santa Cruz, and Pima Counties, 

 mostly 3,000 to 5,000 feet, rocky hills and open ground, July to Octo- 

 ber. Oklahoma to Arizona, Mexico, and southern Florida; Argentina. 



This species affords good grazing and is sometimes cut for hay. 



