Part 3, 1915] 



POACEAE 



207 



XXX. Lanuginosa. 

 Spikelets not more than, 2 mm. long. 



Plants grayish, velvety-pubescent. 



Spikelets 1.4-1.5 mm. long; autumnal leaf -blades involute- 

 pointed (see also P. albemarlense) . 

 Spikelets 1.8-2 mm. long; autumnal leaf -blades flat. 



Plants dark-green or olive-green when dry; spikelets 1.9-2 mm. 

 long. 



Branching sparingly from middle nodes, erect; vernal leaf- 



blades sparingly pilose on upper surface. 

 Branching freely from lower nodes, decumbent; vernal leaf- 

 blades puberulent on both surfaces. 

 Plants light-green or yellow-green when dry. 



Autumnal phase prostrate, branching from the base and 

 lower nodes, forming close mats; leaf -blades not ciliate; 

 a species of hot springs. 

 Autumnal phase ascending or spreading, branching from 

 middle and upper nodes; leaf -blades reduced, fas- 

 cicled, strongly ciliate. 



Vernal culms 40-70 cm. high; autumnal culms usually 



40-50 cm. long; southeastern United States. 

 Vernal culms 20-40 cm. high; autumnal culms usually 

 20-30 cm. long, the early branches zigzag; West 

 Indies. 

 Plants pubescent, often villous, but not velvety. 



Culms conspicuously pilose with long, horizontally spreading hairs, 



branching before expansion of primary panicles. 

 Culms variously pubescent, if pilose the hairs not long and hori- 

 zontally spreading. 



Vernal leaf-blades glabrous or nearly so on the upper surface, 

 firm in texture. 

 Autumnal culms branching from the lower nodes, forming 



a spreading bunch 10-^15 cm. tall; Pacific Slope. 

 Autumnal culms branching from the middle nodes, forming 

 widely spreading mats; Atlantic Slope (see also form of 

 P. Huachucae silvicola). 

 Vernal leaf -blades pubescent on the upper surface, sometimes 

 pilose near the base and margins only. 

 Spikelets 1.3-1.5 mm. long; vernal blades long-pilose on the 

 upper surface. 

 Autumnal form widely decumbent-spreading, forming 

 a mat ; vernal culms soon geniculate-spreading ; plants 

 olivaceous. 

 Autumnal form erect or leaning, never forming a mat; 

 plants yellowish -green. 

 Axis of panicle puberulent only; panicle-branches 



not tangled, the lower ascending. 

 Axis of panicle pilose; panicle-branches tangled, the 

 lower drooping. 

 Spikelets 1.6-2 mm. long; vernal blades pilose or pubescent. 

 Upper surface of blades appressed-pubescent, or pilose 

 toward the base only; spikelets 1.6-1.8 mm. long; 

 autumnal phase not decumbent-spreading. 

 Upper surface of blades pilose; spikelets 1.8-2 mm. 

 long; autumnal phase decumbent-spreading. 

 Spikelets obtuse; culms not weak and lax. 



Culms leafy below, branching from the base and 



lower nodes; Maine to Minnesota. 

 Culms evenly leafy, branching from the upper 

 nodes; Pacific Slope. 

 Spikelets pointed; culms weak and lax. 

 Spikelets 2.2 mm. or more long. 

 Spikelets 2.2-2.4 mm. long. 



Pubescence on culms horizontally spreading; autumnal phase 



freely branching. 

 Pubescence on culms appressed or ascending; autumnal form 

 rather sparingly branching. 

 Upper internodes not shortened, the copious pubescence silky. 

 Upper internodes shortened, the leaves approximate, the blades 

 often equaling the panicle; pubescence sparse and stiff. 

 Spikelets 2.7-2.9 mm. long. 



Culms stiff; blades conspicuously ciliate; southern Atlantic coast. 

 Culms weak; blades not ciliate; Pacific coast. 



140, P. auburne. 



141. P. Thurowii. 



142. P. olivaceum. 



147. P. thermale. 



138. P. lanuginosum 



139. P. acuminatum. 



143. P. praecocius. 



145. P. occidentale. 



137. P. tennesseense 



134. P. albemarlense, 



133. P. meridionale 

 135. P. implicatum. 



136. P. Huachucae. 



144. P. subvillosum. 



146. P. pacificum. 

 148. P. languidum. 



149. P. villosissimum. 



150. P. pseudopubescens. 



152. P. scoparioides, 



151. P. ovale. 



153. P. shastense. 



XXXI. Columbiana. 



Spikelets 2-3.2 mm. long, mostly elliptic. 

 Winter blades 1-3 cm. long. 



Spikelets 3.2 mm. long; first glume conspicuously distant 



154. P. malacon 



