208 



NORTH AMERICAN FLORA 



[Volume 17 



155. P. Commonsianum. 



156. P. Addisonii. 



157. P. wilmingtonense. 



158. P. tsugetorum. 



159. P. columbianum. 



160. P, oricola. 



161. P. sphaerocarpon, 



162. P. polyanthes. 



163. P. erectifolium, 



171. P. curtifolium. 



Spikelets not more than 2.5 mm. long; first glume not distant. 

 Spikelets about 2.4 mm. (2.2-2.4 mm.) long; panicle open, the 



branches stiffly spreading. 

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

 ascending. 

 Winter blades elongate, 5-10 cm. long; spikelets 2 mm. long; plants 

 blue-green. 

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



Culms crisp-puberulent or appressed -pubescent with crimped hairs; 

 plants bluish- or grayish -green; panicles about 3-7 cm. long. 

 Spikelets 1.8-1.9 mm. long, 

 Spikelets 1.5-1.6 mm. long. 

 Culms appressed- or ascending-pilose; spikelets not more than 1.5 

 mm. long, rounded and turgid; plants olivaceous; panicles rarely 

 more than 3 cm. long. 



XXXII. Sphabrocarpa. 



Culms spreading; leaf -blades obscurely nerved; panicle nearly as broad 



as long. 

 Culms erect or ascending; leaf -blades rather strongly nerved; panicle 

 never more than two thirds as broad as long, usually less. 

 Spikelets 1.5-1.6 mm. long; leaf -blades lanceolate, the upper not 



reduced. 

 Spikelets 1—1.2 mm. long; leaf -blades tapering from base to apex, the 

 upper much smaller than the lower. 



XXXIII. HnsipoivIA. 



Ligules about 1 mm. long; leaf -sheaths, or some of them, sparsely spread - 



ing-pilose. 

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



Leaf -blades prominently white-margined, firm; spikelets densely 

 puberulent. 

 Leaf -blades puberulent beneath, often above; sheaths and some- 

 times lower internodes ascending pubescent. 

 Leaf -blades glabrous ; sheaths glabrous or minutely ciliate only. 

 Uppermost culm leaf -blades much reduced; culms branching 



from lower nodes only, the branches repeatedly branching. 165. P. albomarginatum, 

 Uppermost culm leaf -blades about as long as the others; culms 

 bearing short branches from the upper and middle nodes. 

 Leaf-blades not white-margined or very obscurely so (or if white 

 margin is evident, spikelets only 1.1 mm. long); spikelets gla- 

 brous or puberulent. 

 Culms branching only at the base; plants soft, light -green. 

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

 Spikelets glabrous. 



Spikelets 1.1—1.2 mm. long; leaf -blades rarely as much as 



5 cm. long. 

 Spikelets 1.2-1.5 mm. long. 



Leaf -blades elongate, at least some of them 8-10 cm. 



long. 

 Leaf -blades not more than 3 cm. long. 

 Spikelets puberulent. 



Spikelets 1.1 mm. long; winter leaf -blades bluish-green, not 



glossy. 

 Spikelets 1.3-1.5 mm. long. 



Leaf -blades involute, falcate, with long stiff marginal 



hairs near the base; plants stiff and wiry. 

 Leaf -blades not involute, or at top only, not falcate. 

 Plants bright-green; winter blades conspicuous, 



glossy-green. 

 Plants olive; winter blades not conspicuous nor 

 glossy. 



164. P. tenue. 



166. P. trifolium. 



170. P. vernale. 



172. P. chamaelonche, 



173 

 169 



P. 

 P. 



glabrifolium. 

 ensifolium. 



168. P. concinnius. 



174, P. breve. 



167. P. flavovirens, 



XXXIV. Lancearia. 



Spikelets 1.5-1.6 mm. long. 

 Spikelets 2 mm. or more long. 



Leaf -blades not more than 6 mm. wide (or, if wider, puberulent on the 

 upper surface) ; fruit smooth and shining. 

 Spikelets not more than 2.1 mm. long. 



Leaf -blades firm, glabrous above; culms stiffly ascending. 

 Leaf -blades lax, softly puberulent on both surfaces ; culms de- 

 cumbent. 

 Spikelets 2.4-2.6 mm. long; leaf -blades narrowed toward the base. 

 Leaf -blades, or some of them, at least 8 mm. wide, glabrous on the 

 upper surface; fruit papillose -roughened. 



XXXV. Oligosanthia. 

 Nodes bearded; leaf -blades velvety-pubescent beneath. 



169. P. ensifolium. 

 175. P. portoricense. 



176. P. lancearium. 



177. P. patulum. 

 179. P. patenti folium, 



178. P. Webber ianum. 



