102 



GR AMINE AE (GRASS FAMILY) 



w. Ligule less than 1 mm. long (r. 

 X. Blades velvety on both surfaces ; nodes bearded 

 X. Blades not velvety ; nodes not bearded y. 



y. Culms crisp-puberulent 



y. Culms glabrous *. 



z. Spikelets 1.5-1.8 mm. long. , 



Culm-blades not over 2 cm. long ; spikelets elliptical 

 Culm-blades 6-20 cm. long; spikelets spheroidal. 

 Panicle not more than half as wide as long ; blades 



stronglv nerved ....... 56. P. polyanthes. 



Panicle nearly as wide as long ; blades not 



strongly nerved 55. P. sphaerocarpon. 



s. Spikelets 2.2-2.8 mm. long. 



Blades cordate, 1.2-2 cm. wide .... 

 Blades not cordate, 0.6-1.2 era. wide. 

 Blades erect ; fruit covered .... 



Blades spreading ; fruit exposed at summit 

 V. Sheaths pubescent a. 

 a. Sheaths puberulent, not pilose. 



Spikelets elliptical, 2.6 mm. long 



Spikelets obovoid -turgid, 2 mm. long. 

 Plants erect or spreading ; blades glabrous above . 

 Plants prostrate or creeping ; blades puberulent on both 



surfaces 61. P. patulum. 



a. Sheaths spreading- or appressed-pilose or velvety h. 

 b. Plants grayish-velvety throughout. 



Spikelets 2.6 mm. long 



Spikelets 1.8 mm. long 



Spikeletsl.3-l.4mm. long, very turgid .... 

 b. Plants not velvety c. 

 c. Spikelets 2.7-3 mm. long. 



Blades papillose-hirsute on both surfaces 

 Blades glabrous or sparsely silky above .... 

 c. Spikelets less than 2.5 mm. long d. 

 d. Spikelets ovate, pointed; blades 1.5-2.5 dm. long; pani- 



34. P. annulv/m. 

 58. P. Ashei. 



54. P. ensifolium^ 



57. P. commutatum. 



P. horeale. 



P. maUainuiikeetensi 



58. P. Ashei. 



60. P. lancearium. 



P. Hcoparium. 

 P. lanugino/ium. 

 P. auburn e. 



Wilcoxianum. 

 ovale. 



cle 1.2-2.5 dm. long 



d. Spikelets obovate or elliptical, blunt ; blades and panicle 



P. scabriusculum. 



shorter e. 

 e. Pubescence spreading /. 

 /. Spikelets 2.2-2.4 mm. long. 



Plants very villous ; autumnal state prostrate 

 Plants papillose-hispid on sheaths and sparsely 

 hispid on blades; autumnal state erect 

 /. Spikelets 1.3-1.9 mm. long g. 



g. Blades stiff, glabrous above or with a few hairs 

 g. Blades pubescent above, or if glabrous lax h. 

 h. Upper surface of blades with erect hairs 3-5 mm. long. 

 Culms branching very early ; spikelets 1.8- 



1.9 mm. long 



Culms branching after maturity of primary 

 panicle ; spikelets not over 1.5 mm. long. 

 Axis of panicle long-pilose .... 

 Axis of panicle nearly glabrous 

 h. Upper surface of blades with short or some- 

 what appressed pubescence. 

 Blades stiff; spikelets obovate 



48. P. villosUfsimum. 

 47. P. scoparioides. 

 43. P. tennesseense. 



46. P. praecocius. 



40, 



P. implicatum. 

 P. meridionale. 



P. huachucae. 



Blades lax ; spikelets elliptical 

 e. Pubescence not spreading 



(38) P. huachucae, v. sil'vicola. 



ligule 



i. Culms crisp-puberulent or crisp-pubescent 

 nearly obsolete. 

 Spikelets 1.9 mm. long ; blades 5-6 cm. long ; 



plants blue-green 



Spikelets 1.7 mm. long; blades 3-5 cm. long; 



plants gray-green 53. P, 



i. Culms with short or long appressed pubescence .^ 



52. P. Uugetorum. 



columhianum. 



Ligule obsolete or nearly so. 



Spikelets 2.5 mm. long . . . . 50. P. Commonsianum, 



Spikelets 2-2.2 mm. long 51. P. Addisonii. 



Ligule 2-3 ram. long. 



Pubescence on lower sheaths spreading 

 Pubescence on lower sheaths appressed. 

 Blades glabrous on upper surface ; spikelets 



1.2 ram. long 

 Blades pubescent on upper surface ; spikelets 

 1.5-1.9 mm. long. 

 Spikelets 1.5 mm. long ; panicles not over 



3 cm. long 41. P. oricola. 



Spikelets 1.9 mm. long ; panicles 3-5 Cm. 



long . , , , . . , . 42. P. mbtillosvm. 



40. P. meridionale. 



. 37. P. leucothrix. 



