MANUAL OF THE GRASSES OF THE UNITED STATES 631 



Blades sparsely hispid on the upper surface; spikelets 2.2 to 2.3 mm. long; first 



glume pubescent 63. P. scoparioides. 



Upper internodes not shortened, the copious pubescence silky. 



61. P. PSEUDOPUBESCENS. 



Spikelets 2.7 to 2.9 mm. long. 



Culms stiff; blades conspicuously ciliate; southern Atlantic coast 62. P. ovale. 



Culms weak; blades not ciliate; Pacific coast 64. P. shastense. 



9. Columbiana 



la. Spikelets 2 to 3.2 mm. long, mostly elliptic. 

 Winter blades 5 to 10 cm. long; spikelets 2 mm. long; plants blue-green. 



69. P. wilmingtonense. 

 Winter blades 1 to 3 cm. long. 



Spikelets 3.2 mm. long; first glume conspicuously distant 65. P. malacon. 



Spikelets not more than 2.9 mm. long; first glume not distant. 



Spikelets 2.8 to 2.9 mm. long; vernal blades 8 to 15 cm. long 66. P. deamii. 



Spikelets not more than 2.4 mm. long; vernal blades not more than 8 cm. long. 

 Spikelets about 2.4 mm. (2.2 to 2.4 mm.) long; panicle open, the branches stiffly 



spreading 67. P. commonsianum. 



Spikelets 2 to 2.1 mm. long; panicle rather dense, the branches ascending. 



68. P. ADDISONII. 

 lb. Spikelets not more than 1.9 mm. long, obovate, turgid. 

 Culms crisp-puberulent or appressed-pubescent with crimped hairs; plants bluish or gray- 

 ish green; panicle about 3 to 7 cm. long. 



Spikelets 1.8 to 1.9 mm. long 70. P. tsugetorum. 



Spikelets 1.5 to 1.6 mm. long 71. P. columbianum. 



Culms appressed or ascending-pilose; plants olivaceous; panicle rarely more than 3 cm. 

 long. Spikelets not more than 1.5 mm. long, rounded and turgid. 

 Spikelets 1.5 mm. long; culms rather stout; autumnal phase branching from all the 



nodes 72. P. oricola. 



Spikelets 1.3 to 1.4 mm. long; culms very slender; autumnal phase with branches 

 mostly aggregate toward the summit 71. P. columbianum var. thinium. 



10. Sphaerocarpa 

 Culms spreading; blades obscurely nerved; panicle nearly as broad as long. 



73. P. SPHAEROCARPON. 



Culms erect or ascending; blades rather strongly nerved; panicle never more than two-thirds 

 as broad as long, usually less. 

 Spikelets 1.5 to 1.6 mm. long; blades lanceolate, the upper not reduced. 



74. P. POLYANTHES. 



Spikelets 1 to 1.2 mm. long; blades tapering from base to apex, the upper much smaller 

 than the lower 75. P. erectifolium. 



11. Ensifolia 



Ligules about 1 mm. long; sheaths or some of them sparsely spreading-pilose. 



83. P. curtifolium. 

 Ligules obsolete or nearly so ; pubescence if present not spreading. 



Blades prominently white-margined, firm; spikelets densely puberulent. 



Blades puberulent beneath, often above; sheaths and sometimes lower internodes 



ascending-pubescent 76. P. tenue. 



Blades glabrous; sheaths glabrous or minutely ciliate only. 



Uppermost culm blades much reduced; culms branching from lower nodes only, the 



branches repeatedly branching 77. P. albomarginatum. 



Uppermost culm blades about as long as the others; culms bearing short branches 



from the upper and middle nodes 78. P. trifolium. 



Blades not white-margined or very obscurely so (or if white margin evident spikelets only 

 1.1 mm. long); spikelets glabrous or puberulent. 



Culms branching only at base; plants soft, light green 82. P. vernale. 



Culms branching at the nodes; plants firm or at least not soft. 

 Spikelets glabrous. 



Spikelets 1.1 to 1.2 mm. long; blades rarely as much as 5 cm. long. 



84. P. chamaelonche. 

 Spikelets 1.2 to 1.5 mm. long. 



Blades elongate, at least some of them 8 to 10 cm. long. 



85. P. GLABRIFOLIUM. 



Blades not more than 3 cm. long 81. P. ensifolium. 



