PIPER FLORA OF THE STATE OF WASHINGTON. 107 



ARISTIDA. 



1. Aristida purpurea robusta (Merrill). 



Aristida longiseta robusta Merrill, U. S. Dept. Agr. Div. Agrost. Circ. 34: 5. 1901. 



Type locality: "Indian Creek, Montana." 



Range: South Dakota to British Columbia, south to Nebraska and Wyoming. 



Specimens examined: Alma, fi'Zmer 536; Rock Island, Saridfrer^fcfe Zei6er^ 439; Spokane, 

 Piper 2597; Wawawai, Brodie, July, 1898; Kelly's Bar, Snake River, Brodie, July, 1898; 

 Cow Creek, Griffiths & Cotton 288; Lyons Ferry, Griffiths & Cotton 547. 



Zonal distribution: Upper Sonoran and Arid Transition. 



Nuttall's type of A. purpurea in the Philadelphia Academy of Sciences was, in my 

 opinion, misunderstood by Mr. Merrill. The type certainly belongs to the group of forms 

 Merrill includes under A. longiseta Steud., and has nothing to do with the species with 

 which Merrill associates the name purpurea. 



STIPA. 



Awns 10 to 20 times longer than the lemmas. 



Plants glabrous 8. S. comata. 



Plants pubescent 8a. S. comata intonsa. 



Awns 4 to 7 times longer than the lemma. 

 Awns plumose. 



Ligule 1 mm. long or less. 



Sheaths glabrous 1 . S. occidentalis. 



Sheaths pubescent 2. S. ehneri. 



Ligule 2 to 4 mm. long 3. S. thurberiana. 



Awns only slightly pubescent or scabrous. 



Callus very short, obtuse; spikelets stout 4. S. lemmoni. 



Callus acute or acuminate. 



Sheaths pubescent r>. S. vnlliamsii. 



Sheaths smooth or only scabrous. 



Awns 1 to 3 cm. long 6.5. minor. 



Awns 3.5 to 6 cm. long 7. 5. nelsoni. 



1. Stipa occidentalis Thurb. Bot. King Explor. 380. 1871. 

 Stipa stricla Vasey, Bull. Torr. Club 10: 42. 1883. 



Stipa strida sparsijlora Vasey, Contr. Nat. Herb. 3: 51. 1892. 



Stipa oregonensis Scribner, U. S. Dept. Agr. Div. Agrost. Bull. 17: 130. 1899. 



Type locality: "Yosemite Trail, California." 



Range: Washington to Nevada and California. 



Specimens examined: Ellensburg, Piper 2583; Twenty-five Mile Creek, Okanogan 

 County, Gorman 617; Clealum, Henderson 2254; Mount Adams, Henderson 2256; Ophir, 

 Elmer 515; without locality, Suksdorf in 1882; Mount Baldy, Cotton 1755; Weuache 

 Mountains, Cotton 1675; Stehekin, Griffiths cfc Cotton 21. 



Zonal distribution: Arid Transition. 



2. Stipa elmeri Piper & Brodie, U. S. Dept. Agr. Div. Agrost. Bull. 11:46. 1898. 

 Stipa vindula pubescens Vasey, Contr. Nat. Herb. 3:50. 1892, not Stipa pubescens R. Br. 



1810. 



Type locality: Empire City, Nevada, according to the label on the type specimens. 



Range: Washington to Nevada. 



Specimens examined: West Klickitat County, i'MArsdor/", June 17,1883; Nile, Henderson 

 2253; Cascade Mountains, Vasey in 1889; Chelan, Elmer 487; Ophir, Elmer, August, 1897; 

 Spokane, Piper 2276, 2601 ; Steamboat Rock, Griffiths & Cotton 441. 



Zonal distribution: Arid Transition. 



