130 CONTRIBUTIONS FROM THE NATIONAL HERBARIUM. 



Panicles close. 



Lemmas scabrous; leaves very 



scabrous 30. P. cottoni. 



Lemmas smooth ; leaves smooth . 3\. P. cusickii. 

 Leaves not filiform. 



Stems low, 5 to 20 cm. high; grasses 

 of the highest mountains. 



Leaves soft; panicle purple, very 



short; plants 5 to 10 cm. high. 32. P. lettermani. 

 ' ■ Leaves rather rigid ; panicle pale, 



narrow, elongated; plant 10 to 



20 cm. high 33. P. sulcsd^rfii. 



Stems taller, usually 20 to 40 cm. 

 high; mostly grasses of rupestrine 

 habitat. 



Panicle close, erect; leaves flat. 

 Lemmas pubescent at base; 

 leaves rather narrow, some- 

 times folded 21. P. sandbergii. 



Lemmas glabrous; leaf 

 blades broader. 



Leaf blades soft 22. P. paddensis. 



Leaf blades firm, very 



short 23. P. curtifolia. 



Panicles loose; leaves narrow, 

 flat or involute. 



Ligules of the sterile shoots 

 obsolete; of the culm leaves 



short and truncate 24. P. multnomae. 



Ligules well developed on all 

 the leaves. 

 \ Low plants 5 to 10 cm. 



high; panicle small, 



with divaricate rays 



and few spikelets. . . . 25. P. vaseyocJdoa. 



Taller; 10 to 30 cm. 



- . . high ; panicle less 



spreading, with many 

 ^ spikelets. 



Panicle loose; 

 . \ glumes thin, 



blades involute.. 26. P. gracillima. 

 Panicle close; 

 glumes firm, 

 blades flat 27. P. saxatilis. 



1. Poa annua L. Sp. PI. 1: 68. 1753. 



Type locality: "Habitat in Europa ad vias. " 



Specimens examined: Near Ellcnsburg, Piper 2617; Vasey 181; North Yakima, Watt, 

 August, 1895; Southbend, Spillman, August 17, 1899; Steptoe, Vasey 1; Pullman, Piper 

 2769. 



Abundantly introduced, but in some localities apparently native. 



2. Poa compressa L. Sp. PI. 1 : 69. 1753. Canada bluegrass. 

 Type locality: "Habitat in Europae et Americae septentrionalis siccis, muris, tectis." 



