MANUAL OF THE GRASSES OF THE UNITED STATES 607 



11. Ensifolia 



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



80. 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 inter- 

 nodes ascending-pubescent 73. 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, 74. P. albomarginatum. 



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



branches from the upper and middle nodes 75. 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__ 79. 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. 



81. P. CHAMAELONCHE. 



Spikelets 1.2 to 1.5 mm long. 



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



82. P. GLABRIFOLIUM. 



Blades not more than 3 cm long 78. P. ensifolium. 



Spikelets puberulent. 



Spikelets 1.1 mm long. Winter blades bluish green, not glossy. 



77. P. CONCINNIUS. 



Spikelets 1.3 to 1.5 mm long. 



Blades involute, falcate, with long stiff hairs on margin near base. 



Plants stiff and wiry 83. P. breve. 



Blades not involute, or at tip only, not falcate. 



Plants bright green; winter blades conspicuous, glossy green. 



76. P. FLAVOVIRENS. 



Plants olive; winter blades not conspicuous nor glossy. 



78. P. ENSIFOLIUM. 



12. Lancearia 



Spikelets, 1.5 to 1.6 mm long 84. P. portoricense. 



Spikelets 2 mm long or more. 



Blades, or some of them at least 8 mm wide, glabrous on the upper surface; 



fruit papillose-roughened 87. P. webberianum. 



Blades not more than 6 mm wide (or if wider, puberulent on the upper surface) ; 

 fruit smooth and shining. 

 Spikelets 2.4 to 2.6 mm long. Blades narrowed toward the base. 



88. P. PATENTIFOLIUM. 



Spikelets not more than 2.1 mm long. 



Blades firm, glabrous above; culms stiffly ascending. 85. P. lancearium. 

 Blades lax, softly puberulent on both surfaces; culms decumbent. 



86. P. PATULUM. 

 13. Oligosanthia 



Nodes bearded; blades velvety-pubescent beneath. 



Plants lax, soft- velvety throughout; spikelets not more than 3 mm long. 



90. P. MALACOPHYLLUM. 



Plants stiff, pubescence harsh; spikelets about 4 mm long_ 94. P. ravenelii. 

 Nodes not bearded (or but obscurely so in P. wilcoxianum) ; blades not velvety. 

 Panicle narrow, branches erect, or spreading only at anthesis. Blades erect. 

 Spikelets not more than 3 mm long; blades not more than 6 mm wide. 



89. P. WILCOXIANUM. 



Spikelets 3.7 to 4 mm long; blades 8 to 20 mm wide. 



Blades papillose-hispid 95. P. leibergii. 



Blades glabrous on both surfaces 96. P. xanthophysum. 



Panicle about as wide as long. 



Spikelets narrowly obovate, subacute; plants olivaceous, appressed-pubes- 



cent 93. P. oligosanthes. 



Spikelets broadly obovate, turgid, blunt; plants green, the pubescence, if 

 present, not appressed. 

 Blades erect, not more than 6 mm wide; plants copiously hirsute through- 

 out 89. P. WILCOXIANUM. 



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