PIPER FLORA OF THE STATE OF WASHINGTON. 551 



Range: Washington, Oregon, Missouri, Tennosseo. 



Specimens examined: White Salmon, 5'mI.sv/o// 189; Wawawai, Pi/^tv- 1593. 



Zonal distribution: Humid Transition. 



3. Xanthiuni oligacanthum sp. no v. 



Stem erect or spreading, 30 to 60 cm. high, sparsely hispid; leaves reniform-orbicular, 

 obscurely lobed and crenate, harshly scabrous, hispid on both faces, the petioles as long 

 or longer than the blades; fi-uiting involucres oblong, the body l.T) cm. long, 5 to 7 mm. 

 thick, the stout beaks somewhat incurved; prickles 15 to 25, uncinate-tipped, about as 

 long as the diameter of the fmit; surface of the fruit and base of prickles pubescent. 



Bolles, Walla Walla County, Piper, September IS, 1893; also found at Waitsburg l)y 

 Horner (no. B 272). The type is in the National Herbarium. This differs from any other 

 American species in the small size of tiie fruit and the relatively few pi'ickles. 



4. Xanthium affine Greene, Pittonia 4: 60. 1899. 



Type locality: " Sandy banks of the Columbia River, Klickitat County, Washington." 

 Collected by Suksdorf. 



Range: Washington. 



Specimens examined: West Klickitat County, Sulsdorf 1583: Spokane, KrecKjer 537; 

 Piper September 1, 1899. 



5. Xanthiuni varians (ireene, Pittonia 4: 59. 1899. 



Type locality: "Sandy banks of tlie Columl)ia River, Klickitat County, Washington." 

 Collected by Suksdoi'f. 

 Range: Washington. 

 Specimens examined: West Klickitat County, (SmA-si^oz/L^SS; Waitsluirg, //o/ne;- 273 B. 



Xanthium echinatum Mun-. and Xanthium strumarium L. are names which appear 

 in Suksdorf's list, l)ut they are erronet)Us determinations of some of the above species. 



AMBROSIA. Ragweed. 



Leaves all opposite; receptacle without chalf 1. ^1. frijida. 



Leaves opposite and alternate; receptacle chaffy. 



Fruiting involucre spiny; leaves thin 2. A. arteinisiaefolia. 



Fruiting involucre tuhercled ; leaves thick 3. .1. psilosfachya. 



1. Ambrosia trifida L. Sp. PL 2: 987. 1753. 

 Type locality: " In Virginia, Canada. " 



Range: Saskatchewan and Canada to Texas and Florida. 



Specimens examined: Walla Walla, Piper, August 13, 1897 (introduced). 



2. Ambrosia artemisiaefolia L. Sp. PI. 2: 988. 1753. 

 Ty'pe locality: " Habitat in Virginia; Pennsylvania." 

 Range: British Columbia to Nova Scotia, south to Texas. 

 Specimens examined: Mission, Kreager 495. 



2a. Ambrosia artemisiaefolia diversifolia subsp. nov. 



Leaves becoming progressive!}' less deeply lobed upwai'd, those of tlie upper third of 

 the plant mostly entire, these ovate-lanceolate or lanceolate, acute, narrowed al^riiptly 

 to a subsessile base, 3-nerved. 



On the gravelly banks of Alniota Creek at Alraota, Piper, August 26, 1894 (no. 1837). 

 At this place it seems urKjuestionabl}' to be native. The entire or subentire upper leaves 

 present a peculiar characteristic which does not seem to be approached in any eastern 

 specimens. The plant may represent a distinct species, but in the absence of more abun- 

 dant material it seems 1)est to treat it as above. 



The t3^pe is in the National Herbarium. 



