10:2 



GRAMINEAE (GRASS FAMILY) 



34. P. annulum. 



e. Llgnle less than 1 mm. long x. 

 z. Blades velvety on both surfaces ; nodes bearded 

 ID. BLides not velvety ; nodes not bearded y. 



y. Culms crisp-puberulent . . . . . . . .58. P. As fie i. 



. Culms glabrous *. 

 e. Spikelets 1.5-1.8 mm. long. 



Culm-blades not over 2 cm. long ; splkelets elliptical 54. P. ensifolium. 

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

 Panicle not more than half as wide as long ; blades 

 strongly nerved 



y. 



long ; blades not 



56. P. polyanthes. 



55. P. sph&trocarpon 

 57. P. commutatum. 



P. boreaU. 



P. matt<imukteien 



32. 



33. 



58. P. 



60. P. lancearium. 



Panicle nearly as wide 



strongly nerved . 

 e. Spikelets 8.8-8.8 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 

 . 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. paiulitm. 



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

 b. Plants grayish- velvety througnout. 



Spikelets 2.6 mm. long 68. P. gcoparium. 



Spikelets 1.8 mm. long 44. P. lanuginomim. 



Spikelets 1.3-1.4 mm. long, very turgid .... 45. P.avburne. 

 b. Plants not velvety c. 

 c. Spikelets 2.7-3 mm. long. 



Blades papillose-hirsute on both surfaces . . .67. P. Wilcozianum. 

 Blades glabrous or sparsely silky above .... 49. P. ovaie. 

 c. 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 69. P. 



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



shorter e. 



6. 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. 



ff. 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 ." 46. P. praecociu*. 



Culms branching after maturity of primary 



panicle ; spikelets not over 1.5 mm. long. 



Axis of panicle long-pilose . . . . 89. P. Smplicalum. 

 Axis of panicle nearly glabrous . . . 40. P, meridional*. 

 A. Upper surface of blades with short or some- 

 what appressed pubescence. 



Blades stiff ; spikelets obovate . . . .88. P. hnachucat. 

 Blades lax; spikelets elliptical (88) P. hua-chucae, v. gilricvla. 



. Pubescence not spreading . 



i. Culms crisp-puberulent or crisp-pubescent; ligule 



nearly obsolete. 

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



plants blue-green 



Spikelets 1.7 mm. long; blades 8-5 cm. long 



plants gray-green 



i. Culms with short or long appressed pubescence j. 

 j. Ligule obsolete or nearly so. 



Spikelets 2.5 mm. long 



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



J. Ligule 2-3 mm. long. 



Pubescence on lower sheaths spreading . . 40. P. meridional*. 

 Pubescence on lower sheaths appressed. 

 Blades glabrous on upper surface ; splkelets 



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 



48. P. villosi**imum. 

 47. P. scoparioidea. 

 43. P. tenne*Keen*6. 



52. P. hvgetorum, 



53. P. Columbia num. 



50. P. Commoneianum. 



87. P. 



Spikelets 1.9 mm. long ; panicles 8-5 cm. 

 long ........ 



41. P. oricola. 



42. P. tvbnliotum. 



