102 



GRAMINEAE (GRASS FAMILY) 



w. Lifule less than 1 inm. long (C. 

 X. Blades velvety on both surfaces ; nodes bearded . , . 34. P, annulwm. 

 00. Blades not velvety ; nodes not bearded y, 

 y. Culms crisp-puberulent . . . . . . • . 58. /*. Aahei, 



y. Culms glabrous s. 



a. Splkelets 1.5-1.8 mm. long. 



Culm-blades not over 2 cm. long ; spikelets elliptical 54. P. ensifoMttm, 

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

 Panicle not more than half as wide as long ; blades 



strongly nerved 56. P. polyanihea. 



Panicle nearly as wide as long ; blades not 



strongly nerved 55. P. sphaeroearpon 



jff. Spikelets 2,2-2.8 mm. long. 



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

 Blades not cordate, 0.6-1.2 cm. wide. 

 Blades erect ; fruit covered .... 



Blades spreading ; fruit exposed at summit 

 K Sheaths pubescent a. 

 a. Sheaths puberulent, not pilose. 



Spikelets elliptical, 2.6 mm. long 



Spikelets obovold-turgid, 2 mm. long. 

 Plants erect or spreading ; blades glabrous above . 

 Plants prostrate or creeping ; blades pubenulent on both 



surfaces 61. P. patulum, 



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

 i>. Plants grayish- velvety througnout. 



Spikelets 2.6 mm. long . . ... 



Spikelets 1.8 ram. long 



Spikelets 1.3-1.4 mm. long, very turgid 

 &, Plants not velvety c. 

 c. Spikelets 2.7-3 mm. long. 



Blades papillose-hirsute on both surfaces . . .67. P. Wileoxianum, 

 Blades glabrous or sparsely silky above . . , , 49. P. ovale, 

 V. Spikelets less than 2.5 mm. long d. 

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

 cle 1.2-2.5 dm. long 



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

 shorter e. 

 9. 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 A. 

 A. 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 . . . . 39. P. implicat-mn. 

 Axis of panicle nearly glabrous . . . 40. P, meridionale. 

 h. Upper surface of blades with short or some- 

 what appressed pubescence. 

 Blades stiff; spikelets obovate . . . .88. P. h-naehvca e. 

 (83) P. hua-oiiucae, v. silmcola. 



57. P. commuiatum. 



P. horeale. 



P. fnaUaniuHkeeiense 



58. P. Aahei. 



60. P. lancecbrium. 



68. P. ecoparium. 



44. P. laTi/uginoimm. 



45. P. auburne. 



Q. P. 8cahriu80iUum. 



48. P. villosissimwn 

 47. P. scoparioides. 

 43. P. tennesfieeiise. 



46, P. praecociris. 



Blades lax; spikelets elliptical 

 •• Pubescance not spreading i. 



i. Culms crisp-pnberulent or crisp-pubescent; llguie 

 nearly obsolete. 

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



plants blue-green 



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



plants gray-green 



i. Culms with short or long appressed pubescence^. 

 J, Ligule obsolete or nearly so. 



Spikelets 2 5 mm. long ...... 



Spikelets 2-2.2 ram. long 



J. Ligule 2-3 mm. long. 



Pubescence on lower sheaths spreading 

 Pubescence on lower sheaths appressed. 

 Blades glabrous on upper surface ; spikelets 



1.2 mm. long 



Blades pubescent on upper surface ; spikelets 

 1.5-1.9 mm, long. 

 Spikelets 1.5 mm. long; panicles not over 



3 cm. long 



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

 long ... «... 



52. P. tsugetorum. 



53. P. colv/nihianum. 



Comm oneianum 

 Addisonii. 



40. P. meridionale. 



87. P, leuoothrix. 



41. P. oricola. 



42. P. 8't^vWosum. 



