FLOWERIXG PLANTS AXD FERXS OF ARIZONA 965 



7. Outer achenes only moderately shorter than the inner ones and not 

 conspicuously broader: awns usually 3 or 4._ 3. B. bipixnata. 



7. Outer achenes conspicuously shorter and broader than the inner 



ones, usually not more than half their length: awns 2, sometimes 



3 4. B. BIGELOVII. 



6. Heads cylindric or subcylindric, 5- to 13-flowered (8). 



8. Leaf divisions filiform or narrowly linear (1 mm. wide or less); 



achenes glabrous; heads 5- to 9-flowered. 



8. B. HETEROSPERMA. 



8. Leaf divisions lanceolate or ovate to linear, usually more than 1 



mm. wide (9). 



9. Heads subsessile or short -peduncled; achenes glabrous; outer 



phyllaries linear-spatulate, 5 to 8 mm. long, or longer; leaf 



divisions mostly linear or linear-oblong, 1.5 to 3.5 mm. 



wide 6. B. lemmoni. 



9. Heads long-peduncled; achenes antrorse-hispidulous above; outer 

 phyllaries minute, slenderly subulate or filiform-subulate, less 

 than 3 mm. long; leaf divisions broader, mostly lanceolate. 



7. B. LEPTOCEPHALA. 



1. Bidens laevis (L.) B. S. P., Torre}' Bot. Club Mem. 5: 337. 1894. 



Helianthus laevis L., Sp. PL 906. 1753. 



Bidens chrysanthemoides Michx., Fl. Bor. Amer. 2: 136. 1803. 



Bidens persicaefolia Greene, Pittonia 4: 266. 1901. 



Known in Arizona only from the Bradshaw Mountains, southern 

 Yavapai County (Tourney 6S0, type of B. persicaefolia) , and the 

 Santa Cruz River {Pringle in 1881) . Massachusetts to Florida, Arizona, 

 and California, south to South America. 



2. Bidens pilosa L., Sp. PL 832. 1753. 



Chiricahua, Huachuca, Patagonia, and Baboquivari Mountains 

 (Cochise, Santa Cruz, and Pima Counties), 3.500 to 5,000 feet. 

 Florida to California; tropical and subtropical regions of the world. 



The typical form, with discoid heads, has been reported from 

 Arizona but has not been seen by the writer. The principal Arizona 

 form is var. radiata Schultz Bip. (B. leucantha (L.) Willd.), with 5 or 

 6 conspicuous white rays 7 to 15 mm. long. Other Arizona speci- 

 mens are intermediate between var. radiata and the typical form, 

 e. g., a collection in the Mule Mountains, Cochise County {Harrison 

 and Kearney 6237). 



3. Bidens bipinnata L., Sp. PL 832. 1753. 



Mule and Huachuca Mountains (Cochise County), Tumacacori 

 Mission (Santa Cruz County), 3,000 to 6,000 feet, rich alluvial soil, 

 August and September. Rhode Island to Kansas, southeastern Ari- 

 zona, and California, southward to South America; also in the Old 

 World. 



Specimens from Arizona closely approach the preceding and the 

 next following species. 



4. Bidens bigelovii A. Gray in Torr., U. S. and Mex. Bound. Bot. 91. 



1859. 

 Sierra Ancha (Gila County), Chiricahua and Huachuca Mountains 

 (Cochise County), Santa Rita Mountains (Pima County), about 6,000 

 feet, stream banks and moist shady places, July to October. Colorado 

 to western Texas, New Mexico, Arizona, and Sonora. 



