240 



CONTRIBUTIONS FROM THE NATIONAL HERBARIUM. 



Autumnal form spreading, with geniculate nodes and elongated, arched internodes, 

 rather sparingly branching from the middle nodes, the primary branches elongated, 

 the ultimate branchlets shorter than the internodes. 



Fig. 256.— Distribution of P. shastense: 



DISTRIBUTION. 



Known only from Castle Crag, Shasta County, California, where it is found in 

 meadows. 



California: Castle Crag, Greata in 1899, Hitchcock 3072. 



Columbiana. — Culms stiff, pubescent with appressed or ascending villous hairs, or 

 crisp-puberulent, the sheaths pubescent like the culms or nearly glabrous; 

 ligules usually less than 1 mm. long, rarely 1.5 mm. long; blades firm, thick, 

 stiffly ascending, not over 7 mm. wide; spikelets pubescent, 1.3 to 3.2 mm. 

 long, 5 to 9-nerved. Autumnal form freely branching, the branches and stiff 

 blades mostly appressed. With 

 the exception of P. tsugetorum, 

 confined to dunes and dry 

 sands of the Coastal Plain, 

 Massachusetts to Florida. 



The species of this group 

 form a lineal series from P. 

 malacon with spikelets 3.2 

 mm. long to P. columbianum 

 thinium with spikelets only 1.3 

 mm. long. With the excep- 

 tion of P. malacon and P. wil- 

 mingtonense, there are con- 

 necting forms between the successive species in this series, especially between 

 P. commonsianum and P. addisonii, and between P. tsugetorum and P. colum- 

 bianum. These intermediate specimens are, however, comparatively rare. 

 On the other hand, P. oricola and hairy forms of P. tsugetorum make a 

 clear cut division between the Lanuginosa and Columbiana impossible. 

 Spikelets 2 to 3.2 mm. long, mostly elliptic. 



Winter blades elongated, 5 to 10 cm. long; spikelets 2 



mm. long; plants blue green 145. 



Winter blades 1 to 3 cm. long. 



Spikelets 3.2 mm. long; first glume conspicuously 



distant 142. 



Spikelets not over 2.5 mm. long; first glume not 

 distant. 

 Spikelets about 2.4 mm. (2.2 to 2.4 mm.) long; 



panicle open, branches stiffly spreading . .143. 

 Spikelets2 to 2.1 mm. long; panicle rather dense, 



branches ascending 144. 



Spikelets not over 1.9 mm. long, obovate, turgid. 



Culms crisp-puberulent or appressed-pubescent with 

 crimped hairs; plants bluish or grayish green; pan- 

 icles about 3 to 7 cm. long. 



Spikelets 1.8 to 1.9 mm. long 146. 



Spikelets 1.5 to 1.6 mm. long 147. 



Culms appressed or ascending-pilose; spikelets not over 



1.5 mm. long, rounded and turgid; plants oliva- 

 ceous; panicles rarely more than 3 cm. long. 

 Spikelets 1.5 mm. long; culms rather stout; autumnal 



form branching from all the nodes 148. 



P. wilmingtonense . 



P. malacon. 



. commonsianum. 



P. addisonii. 



P. tsugetorum. 

 P. columbianum. 



P. oricola. 



