704 CONTRIBUTIONS FROM THE NATIONAL HERBARIUM. 



KEY TO THE SPECIES. 



Leaves simple. 



Outer bracts about equaling the inner; achenes not corky on 



the angles 1. B. prionophylla. 



Outer bracts as long as the rays or longer; achenes corky on 



the angles 2. B. glaucescens. 



Leaves pinnate or pinnatifid. 



Achenes flat, obovate or cuneate 3. B. frondosa. 



Achenes linear, tetragonal. 



Divisions of the leaves lanceolate, oblong, or ovate. 



Leaves once pinnate, the divisions sometimes pin- 

 natifid into large divisions, thick and firm 4. B. anthriscoides . 



Leaves thrice parted or more into small divisions, 



thin 5. B. bigelovii. 



Divisions of the leaves linear or linear- filiform. 



Divisions of the leaves linear- filiform 6. B. heterosperma. 



Divisions of the leaves linear. 



Heads of achenes narrow, 8 mm. wide or less; 

 bracts nearly glabrous, the outer much 



shorter than the inner 7. B. cognata. 



Heads of achenes broad, 10 mm. wide or more; 

 bracts strongly villous, the outer about 

 equaling the inner 8. B. tenuisecta. 



1. Bidens prionophylla Greene, Pittonia 4: 256. 1901. 

 Type locality: "River Moira, Ontario." 



Range: British America to New Mexico and Illinois. 

 New Mexico: Lower Plaza (Woo ton). Wet ground. 



2. Bidens glaucescens Greene, Pittonia 4: 258. 1901. 



Type locality: "Peculiar to the western mountain districts and the plains adja- 

 cent, but beginning in Kansas, perhaps in Missouri." 



Range: British America to Kansas and New Mexico. 



New Mexico: Farmington; west of Clayton. Wet ground, in the Upper Sonoran 

 Zone. 



3. Bidens frondosa I,. Sp. PI. 832. 1753. 



Type locality: "Habitat in America septentrionali." 

 Range: British America to Florida, Texas, and New Mexico. 



New Mexico: Farmington; Albuquerque. Wet ground, in the Upper Sonoran 

 Zone. 



4. Bidens anthriscoides DC. Prodr. 5: 600. 1836. 



Type locality: " In Mexici Cordillera de Guachilaqua." 



Range: Southern New Mexico, south into Mexico. 



New Mexico: Mesilla Valley (Wooton). Lower Sonoran Zone. 



As nearly as we can judge from the description and from the Mexican specimens 

 examined, this collection belongs here. It exactly matches specimens collected by 

 Palmer near Durango. The plant is closely related to Bidens pilosa L., a species of 

 Mexico and the West Indies found in California, but has different leaves, pubescence, 

 acd achenes. 



5. Bidens bigelovii A. Gray in Torr. U. S. & Mex. Bound. Bot. 91. 1859. 

 Type locality: Banks of the Rio Limpio, Texas. 



Range: Western Texas to southern Arizona and southward. 



New Mexico: Mangas Springs; Kingston; West Fork of the Gila; Organ Mountains. 

 Canyons, in the Upper Sonoran Zone. 



